Bug fix + redesign for C

This release corrects a bug in big-endian output from the 4:2:0 subsample case.
It also reworks the library code to compile as either C++ or C. This allows for easier porting to other embedded environments that may not support C++ or just for personal preference. A demo program for Linux was added which includes file system support. This allows you to use it without having to write any file system callbacks.