This cleans some stuff and improves option handling to add more info about valid choices for some options.
usage: scons [OPTION] [TARGET] ...
SCons Error: `all' is not a valid debug option type, try:
count, duplicate, explain, findlibs, includes, memoizer, memory, objects, pdb, prepare, presub, stacktrace, time
This replaces #55, right?
Yes, this includes #55.