Completely refactored the TurboJPEG C API so that it uses pixel formats instead of...

Completely refactored the TurboJPEG C API so that it uses pixel formats instead of the clunky pixel size + flags combination to define the pixel size and component order.  tjCompress2() and tjTransform() can also now grow the JPEG buffer as needed, which can allow programs to save memory by not pre-allocating the "worst-case" buffer size calculated by TJBUFSIZE().  Converted API documentation to Doxygen.  There is no legacy code remaining, so the refactored version of the library has been re-licensed under a BSD-style license.

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@616 632fc199-4ca6-4c93-a231-07263d6284db