Added the ability to do byte-compilation at build time, currently off

by default (since compiling at install time works just fine).  Details:
  - added 'compile' and 'optimize' options
  - added 'byte_compile()' method
  - changed 'get_outputs()' so it includes bytecode files
A lot of the code added is very similar to code in install_lib.py;
would be nice to factor it out further.