Merge pull request #182 from houqp/pic

finish ffi binding for pic module
clean(build): remove libkoreader-pic module
Merge pull request #183 from houqp/houqp-master

clean(build): remove libkoreader-pic module
doc(blitbuffer): update comment for scale method
chore(blitbuffer): convert tabs to spaces
refactor(pic): detect image type in pic ffi binding