update libk2pdfopt for multithread hinting
temporarily disable ffi blitbuffer module
since paintRect is not working properly in the new
blitbuffer as reported in #274.
Merge pull request #69 from chrox/master

temporarily disable ffi blitbuffer module
update mupdf to version 1.3
update k2pdfopt to version 2.02
link mupdf library to k2pdfopt
Merge pull request #70 from chrox/master

update mupdf to version 1.3 & update k2pdfopt to version 2.02
fix failed checkout of mupdf 05219d0
Merge pull request #71 from chrox/master

fix failed checkout of mupdf 05219d0
remove USE_FIXED_POINT flag
since fixed-point algorithm is a buildin feature in k2pdfopt now.
Merge pull request #72 from chrox/master

remove USE_FIXED_POINT flag
update mupdf patch
map word boxes in reflowed page to boxes in native page
Merge pull request #74 from chrox/master

map word boxes in reflowed page to boxes in native page
add native to reflow transform in koptcontext
Merge pull request #75 from chrox/master

add native to reflow transform in koptcontext
fix reinit ocr engine when new lang is requested
Merge pull request #76 from chrox/master

fix reinit ocr engine when new lang is requested
add mupdfimg FFI interface
don't build old Lua-C-API mupdfimg.c