update k2pdfopt to version 2.00
Merge pull request #58 from hwhw/ffi-experiments

FFI: Blitbuffers, Freetype
Merge pull request #59 from chrox/master

update k2pdfopt to version 2.00
add FFI declarations for SDL and linux input events
add FFI interfacing for SDL (input, graphics)
Merge remote-tracking branch 'upstream/master' into ffi-experiments