Fix MoveRight when tabs are present

Fixing a bug which occured when doing a MoveRight and tabs were present in the line. lineForRow counts tabs as a single char so the cursor does not move to the end of the line.

![recorded](https://cloud.githubusercontent.com/assets/1506585/3672237/1f3f99cc-125c-11e4-9ee4-fc77dc069733.gif)