adding epub support : created Makefiles,modified configuration script

kickoff commit to add ePub support , creating a subdirectory structure and modified makefiles and configure script to
accomodate for ePub . As the sources are done , these will be further changed accordingly .
XML parsing for ePub

using libxml some functions were written which will be used to get keywords,attributes from files such as the ePub container.tried to keep the code generalised so as to facilitate reusability of code.
Added functions to extract epub archive,fixed header

In this commit i added functionality to extract an epub archive to a temporary location.Again i tried to keep the design modular. This will be changed as changes come along.
I also fixed the header to the standard atril backend header. Performed some code cleaning, naming functions as in the atril style of coding.
created a separate directory for minizip content, fixed indentation in configure.ac

Moved ioapi.c unzip.c unzip.h and ioapi.h into a separate directory backend/epub/minizip
Fixed an indentation problem in configure.ac, which was affecting the displayed result.
Also fixed a typo in epub-document.h where i had wrongly named the function.
Created a Makefile for minizip, modified epub Makefile

I created a Makefile for the minizip backend, since i am only using part of that library and modified the epub backend to work with the library.
Also modified the configure script to suit our purpose.
The epub backend can now be compiled using the make command in the epub  directory, although it cannot still be compiled as a part of atril.
Redefined most XML parsing functions,more helpers

This commit as compared to previous ones has much more changes as:

> The xml parsing functions were not generic enough to my needs and needed to be redefined as well as renamed .
> I also set up the document tree for the document using these parsers.All that is now left is to serve these to a webview.
> Fixed a typo in epub-document.h

TODO: integrate with Atril frontend.
Epub backend builds as a part of Atril compilation

Fixed a tabbing error in backend/Makefile.am due to which the epub backend was not a target when building recursilvely, i am not commiting the changes to
epub-document.c as currently it will break the build, hope to fix it and get webkit and mathjax done by the weekend.

Also fixed an error in configure.ac wherin the appearance of AM_LIBTOOL_PROG before AC_CXX_PROG caused a "link:unsupported hardcode properties error" on Linux Mint.
Changed dependecy to webkit-1.0,added web view to window properties

Currently the backend/epub/epub-document.c file has some dummy code, such as that for thumbnails, solely to get it to build. Now that we are done with all functions
that we would possibly need to handle the backend, I am now working now on displaying the document via a webview, starting with this commit where i add a webview to the EvWindow properties. Similar to this I need to put in custom functions for epub, as rendering is done by the layout engine. I will also need to add some epub specific callback functions to the widgets.
Functions for document info and EvPage,other changes

Summary:
 I added functions in the backend to get document info.
 Added a member to evdocument to deal with web documents(ePub) on the frontend.
 Added a webview to the window, that shall replace the Atril view.
 Due to removing the view from the main Atril window, I have given rise to various GTK-critical errors in response to signals, will be sure to suppress these in the next commit.
 Worked towards overall blending in of ePub documents.
More changes to accomodate webview

- Modified configure.ac to use both webkit2 and webkit1 based on gtk version
- Modified Automake file in help/reference/shell/Makefile.am to compile with gtk-doc
- Modified ev-document-model to support epub-documents.
- Modified ev-window for epub documents.
- Modified jobs so epub pages are not rendered.
- Modified ev-document, although I'm not sure if this is necessary.

Still need to figure out where the web view load uri has to be called to actually load pages, from there the puzzle would be much simpler. Hope to get this done in the week, and pick up the pace now that only six weeks of coding remain before final evaluation.
Thumbnails for Epub Documents

This commit is mainly so that any further changes can be reverted to this state. The thumbnails are of very large sizes so I need to fix that, and in general implement thumbnails. Also I am facing an X-windows error, which I can't seem to fix. I feel it may be a problem with webkit-1.0, so will try the build with gtk3 and webkit2. If so is the case, I'll have to work something out for that. Should be able to push a commit soon where the document can actually be read, soon as I figure out the perfect place for the call to load uri.

Other than that more function were modified in accordance with webkit. The error I get when opening the file from the filechooser still persists, I need to fix that too.
Refactored code, created a new EvWebView type

Earlier my approach was to replace the atril view directly with a webview. However as it turned out it was extremely difficult to accomplish much tasks without the document-model. So I created an Extension of the WebKitWebView class, EvWebView so that now we can manipulate the webview as desired. Also having a separate file really helps in terms of clarity.

Please note that there are many empty functions and TODO tags right now, I shall aim to fill these up once the display part is done, probably in this week.

I also added some code on the backend to draw thumbnails when with GTK+-3.0, although I have never tested a GTK+-3.0 build.With GTK+-2.0 you won't get any build errors,  however epub backend won't work right now.

That being said, this commit is mostly because there was a lot of code that was lying in the local repository, and it was best to back it up as a failsafe.
I modified ev-window to accomodate this new data structure, and having an equivalent ev_web_view function for every ev_view function, I can achieve most functionality by filling those functions with Webkit modules.

Other than that on the backend

Other than that there were some minor changes to the code.
Although I did the above, currently I am not able to instantiate the EvWebView because of some class and object type definition errors, due to which I can't display the document.
Files for EvWebView, thumbnails possible with GTK+-2.0

My last commit was supposed to have ev-web-view.c and ev-web-view.h however due to some reason I missed them last time, so here they are now. i am able to achieve thumbnails for my epub however these are of absurdly large size. Still struggling to get the webview done due to thread problems that I am encountering.
Fixing the PDF annotations

Last time I screwed up annotations in PDF, due to a small error, here's the fix.
Fixing the extraction problem

Due to the no fixed guidelines on how content in an ePub file should be arranged, in many cases,in  files with content in subdirectories could not be extracted as those cases were not covered. The new code should not leave any corner cases.
libview: Fix makefile
Merge pull request #1 from stefano-k/epub

libview: Fix makefile
Thumbnails for all documents

Now other problems with webkit. After much fidgeting I was able to resolve the previous problems of threads. However, now there is a different webkit error.
Moving all webkit tasks to main loop jobs
Active properties dialog, other actions

Properties dialog for epub documents, will some basic properties.

Also set toolbar and menu sensitivity for the actions available in epub, will add more(find) once I write the module. Also inverted colors needs to be done with CSS or the like.