This adapts the related graphics code, which is the generic Font API and the
TTF font implementation.
It furthermore adapts the GUI to properly take care of kerning in text input
widgets.
This fixes a problem where opening the keymapper dialog would cause the current game
keymap to be displayed as the active keymap but then changing the keymap selection
back to it would cause the GUI keymap to be displayed as the active one. The GUI keymap
was indeed at the top of the stack but that's not the desired effect.
Also move the pushing and popping of the keymap to Dialog::Open/Close
Also constantify the GUI keymap name
Formerly there was much special handling for the Tooltip dialog in
GuiManager::runLoop. This was replaced by overloading the event handling
functions in Tooltip. Also the Tooltip was adapted to be run like every
other normal dialog.
svn-id: r54337
