misc code and user interface clean-up

[LeonidPryadko]

• additional command-line convenience options, in particular
  • swait (removed this option altogether)
  • start (document it)
  • without arguments (or without the method set), the program should just show a brief help message and exit.
• Make sure sparse L is used with CC method (as opposed to row elimination with G) to check for non-trivial code words in a quantum code.
• Additional clean-up of the recursion subroutine (should we avoid using recursion?)
• Can we reduce the number of dense matrices used (or altogether eliminate them)
• Early termination in RW code word construction if too large weight.