Reduce over-cleaning and improve feedback from build system

Got a bit tired of waiting for bison, flex, and gcc/clang and seeing all their output when all I had changed was some stuff in the Ruby and/or Fancy compilers, so moved those into a separate `clean_parser` Rake task (and added `clean_all`). Your thoughts?

Also adjusted the output from the build system to be a bit more verbose about what's going on and started working on README documentation for the build process.