Review changes:

1. Function style changes.
2. 80-col violations.
3. Better names for things.
4. Arrange constructors so they all take bit width first.
5. Add named signed and unsigned comparison functions and remove the
   corresponding operators.
6. Remove operator&& and operator|| but provide a getBoolValue function which
   converts to bool as comparison against 0. This allows the normal && and
   || operators to be used as if (X.getBoolValue() && Y.getBoolValue())

Note: this still doesn't function 100% yet. I'm working on the bugs now.
llvm-svn: 34353