Improve typescript checker

- Make the errorformat correctly capture multi-line messages
- Add errorformat entries for typescript 0.9.x
- In makeprg, specify module system using the --module flag.
  As of typescript 0.9.1, this flag is required. I've chosen
  CommonJs (as opposed to AMD modules) arbitrarily.

I've tested this against both typescript 0.8 and 0.9, and it works for both.