AGI: Allow mouse use in save / load dialogs
|Reported by:||spookypeanut||Owned by:||sev-|
This patch allows the mouse to be used to select a savegame slot in the AGI engine.
Also fixed a bug which allowed the user to enter a savegame description that was too long, causing a crash.
Ticket imported from: #1637824. Ticket imported from: patches/704.