Fix issue 2479

http://code.google.com/p/iterm2/issues/detail?id=2479

Now normal parser cancels parsing process when parameter length goes over VT100CSIPARAM_MAX.
Canonical parser parsing it completely, but ignores it.

I think there are no reason to cancel or ignore long parameter CSI sequence.

tests/iso6429csi.py (missing now) includes some tests for long parameter CSI sequence. use it if you need.