Initial checkin

This is Gibraltar r3, gotten from
http://svn.code.sf.net/p/libgibraltar/code/trunk.

The paper describing it is at <http://thecenter.uab.edu/media/2011/12/Gibraltar-A-Reed-Solomon-Coding-Library-for-Storage.pdf>; the home page of the code as of this writing is at <http://hpcl.cis.uab.edu/gibraltar-a-reed-solomon-coding-library-for-storage-applications-on-programmable-graphics-processors/>.