Fix fast contrast boost enabling
Cleanup
Fix undefined behavour if current archive and/or directory is not exist longer
Rewrite find next/previous directory code
Fix mistype
Use githib address of GTK_parts.sh instead of dropbox in English translation
Fix archive handling in next/previous directory searching
Fix crash if image->pixbuf[page] is not correct pixbuf
Add clang as one of possible PC build systems (more warnings, I love warnings! *_* )
Small fixes for warnings generated by clang
Fix unificated back/forward directories jumping (still a bit buggy - deep image handling code refactoring needed)