Added additional escape sequences defined in ECMA-48.

Adds:

* cursorToColumn: Absolute columar positioning of the cursor,
* cursorUpLine: Move the cursor up one or more lines, and move it to the
  beginning of the line.
* cursorDownLine: Move the cursor down one or more lines, and move it to the
  beginning of the line.
Merge pull request #21 from jdbernard/master

Added additional escape sequences defined in ECMA-48.