Add -std=c++11 flag to Makefile.
Use C++11 threads in PixelBuffer
Use C++11 threads/mutexes in PDFDocument
Add multithreading abstraction.
Update PDFDocument to use new multithreading abstraction.
Update PixelBuffer to use new multithreading abstraction.
Remove unneeded include
Update ImageDocument to use new multithreading abstraction.
Remove unneeded include.
s/NULL/nullptr/g
Use unique_ptr in Framebuffer::Open().
Use unique_ptr in Framebuffer.
Use unique_ptr in PDFDocument
Update Cache to use C++11 multithreading primitives.
Use unique_ptr and auto to remove some crap.
Use unique_ptr in outlines.
Minor comment change
Fix a race condition in Cache::Get()
Fix another threading issue.
Fix crash due to render cache key comparison