Added a line to Makefile clean target to ignore non-empty directories.
Plugins now set their version using git describe and hash-object.

This information is grabbed by make and passed to gcc using
a compile-time parameter. Currently it uses git-describe to get
the tag/latest-commit (and appends -dirty if the working tree has
unstaged changes) and then appends the git-hash-object generated
hash of the appropriate C file for each plugin.
Added the sma-walsh-pattern-load function.

This allows loading the Walsh table with a repeating array of
0-3 represting the Walsh phase at each step. This function hasn't been
finished yet; I still need to add the actual step that writes to
the mmap regions :p