quit SDL when closing framebuffer
Image now supports png, jpg and tiff files
fix reduced word spacing when floating punctuation is on
update mupdf to version 1.5
update k2pdfopt to version 2.21
fix travis build error
catch up mupdf master branch
Merge pull request #216 from chrox/master

catch up mupdf master branch
add missing munmap declaration
Merge pull request #217 from chrox/master

add missing munmap declaration
fix no "-shared" flag when building libcrypto.so
which may cause building errors like:
```
ld: error in libcrypto.a(cryptlib.o)(.eh_frame); no .eh_frame_hdr table
will be created
```
Merge pull request #218 from chrox/master

fix no "-shared" flag when building libcrypto.so
fix memory leak in freeContext
try catching error when adding markup annotation
add getCoverPageImageData api
create Image from raw buffer
Merge pull request #219 from chrox/master

add getCoverPageImageData api
Two functions I need in setdefaults and search a few times
Merge pull request #220 from WS64/master

Two functions I need in setdefaults and search a few times
refactor out Docview:render calling into a seperate function
so that it won't be called when redering is not neccessary.