Buffer OS X read_raw() for faster loading

Also add attach() and detach() to read_raw() and write_raw() and remove
trailing whitespace on a function.
Merge pull request #8 from tareqak/buffer_osx_reads

Buffer OS X read_raw() for faster loading
21.3 linux fixes, updated readme

- updated the readme with linux build instructions
- fixed a typo in the linux offsets
- reverted the codec changes in linux for a small performance gain
- the 'make install' command works in linux now
21.3 cont. readme fix