FakeVim: Fix yanking in some visual modes

This covers 'Y' in novisual, char and line mode and 'y' in char mode.
Visual block mode is still missing. It also fixes an off-by-one error
when displaying selection in visual char mode.

Reviewed-by: hjk

Merge-request: 1149
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>