Shows icon for when you estimate a requirement

Also added an estimate list listener to GameRequirementModel for
listening for changes to the list of estimates.
Merge remote-tracking branch 'origin/team9dev' into gametree_tweaks
Adds todo
Games list remembers which games were expanded

If you had games expanded in the tree, the tree will remember those when
it refreshes and reopen them if they still exist.
Fixes conflicts
GameTree now remembers which element you selected
Adds feature for automatic game status updating

When games end because of their deadline, they will automatically move
to the completed folder in the tree.
Fixes conflicts
Adds fix for games without deadlines
Fixes weird bugz, all good now
Merge pull request #65 from dbeckwith/gametree_tweaks

Gametree tweaks