-v or --version prints version and exits.

Fixes #829

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/832

Closes #832, closes #829.
Rewrite ParseTreeMapWriter to generate better SourceMap entries.

We were missing the endings of trees. Fixes #766.

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/843

Closes #843, closes #766.
Merge branch 'master' into cps-optimize-ensure-transformed-list
Cleanup with two loops