CFG and XYZ Imports for Matlab

I added a version of readCFG that doesn't require the MEX, and a
readXYZ that can import stuff from Gromacs and other such sources.  Last
I have a yz2cfgKIRKLAND.m that converts files from E. Kirkland's
non-standard .xyz format to .cfg.  I think my readCFG is still
reasonably fast, about 100000 atom positions read-in per second.  In
fact I'm not sure the mex version is faster if I remember correctly.