Read filetype's mime type from the configuration files

This allows custom filetypes to define a mime type, hence the icon
displayed for this filetype;  as well as moving ones for built-in
filetypes out of the code to the configuration files.
Use GIcon for the filetype icon rather than rendered pixbuf

This allows to re-use the icon more easily since it's not rendered at
a particular size but simply an icon description.  It also allows for
implicit icon updating when the theme changes if the display code
implements it (and GTK widgets does).
Add a note in the docs about shell constructs in custom commands
Windows: add default extension to native save dialogs

Fixes bug #1021.

Based on an initial work by Steven Valsesia, thanks!
Fix GTK 2.16 support (oops)
Put Makefile comments at start of line.

In a makefile comments in recipes must start at the beginning of
the line (see [1]).  Thanks to cousteau on IRC.

[1] http://www.gnu.org/software/make/manual/make.html#Recipe-Syntax
Regenerate 16x16 Geany icon to be not cutoff

For some reason, the icon was cutoff in the upper left corner.
From the GIT history, I can't find any real reference for the
reason, so I guess this was just a mistake when convertig the
32x32 icon to 16x16. If anyone knows better, please tell me.
Update of Slovak translation
Add boolean to Pascal keyword list

Pascal has a boolean type (see wikipedia entry) fixes bug #1033
changed filetypes.latex to add Bibtex compilation
updated Lithuanian translation
Merge pull request #228 from gymka/master

Updated Lithuanian translation
Merge pull request #227 from fiacobelli/master

changed filetypes.latex to add Bibtex compilation
Update Doxyfile.in for newer doxygen versions

Automatic config file update by running 'doxygen -u'. All previous settings are
kept but old, deprecated settings were removed to avoid annoying warnings
when executing doxygen (e.g. on the nightly cronjob to update the API docs
on geany.org).
Furthermore, the update tool added a lot of comments above the options,
which is probably good.
Update the HACKING file, explain PR

Add the new way of contributing for geany.
Typo corrections for German language file.
Merge pull request #232 from stefan-it/enhancement/lang-de-corrections

Typo corrections for German language file.
Updated Hebrew translation
Update of German translation
Merge pull request #224 from bestel74/update_HACKING_file

Update the HACKING file: add "pull request" before "patches"