exmode.parser now converts strings to the types given in excmd
signatures.
Messaging now works in both directions (but I haven't made excmds.ts use
the new system yet. Exercise for the reader (see keydown_* state() for a
simple example)).
keys are now being suppressed, but in a pretty stupid way.
I got fed up of not having proper itertools, or str conversions, so I
wrote some. Others have written them in JS, but they were fun to make.
Only the ones I'm using are tested.
