Fix vimode '0' glitch.

Multiplier builder would eat 0 keypress, preventing it from being
interpreted as goto line start.

Now multiplier builder passes on 0 if it is not preceded by a non-zero
digit.
Implement vi goto line (<multiplier>gg).

gg preceded by a multiplier will now mover the cursor to the first
non-whitespace character of that line.

Multipliers appear to be capped at 100 and any multiplier greater than
100 will goto the last line.
Merge pull request #308 from murphyslaw480/vi-dev

NewViMode: Goto Line and fix '0' glitch