Display visual column width in selection

* displays tab width instead of counting hard tabs as 1 character wide,
  which is how TextMate 1 worked.

For example if your tab width is set to 4 and you're on the second
indent position the column will display as 9 (4 * 2) + 1, before this patch
it would display as 3 (1 * 2) + 1.