Added support for named points in the CharView.

1. Added "Name Point..." item to the Point menu of the Charview.
2. Added "Name Point..." item to the selection popup menu for a point.
3. Show point names in CharView, similar to what is done for contours.
4. Added an icon to the tango theme, with a placeholder for the 2012 theme.
Merge pull request #1287 from blipvert/fixes/32

Added support for named points in the CharView.