GUI: Add recent games menu

[Megamouse]

adds a submenu to boot "Boot Recent"

• submenu contains functions "clear list" and "freeze list"
• activated "freeze list" will prevent changes to the list
• successfull boots will be added to the top of the list
• when the list contains 9 items the last will be removed on new addition
• every item has a boot shortcut from Ctrl+1 to Ctrl+9
• games can only be bootet from mainwindow and if emu is not running
• if names are too long they will be shortened like this "This name is waaa(....)aaaay to long"
• on mouse hover you will see a tooltip with the full name
• if the game title is a path it will be shown only as filename while the tooltip remains the path
• remove invalid paths from list on start or boot

[flash-fire]

Looks pretty good. Only a couple things..

1. Small nitpick. const QString& instead of const QString& for small efficiency boost of not copying parameters each time.

2. I haven't thought too hard, but would QActionGroup work better than QLisf<QAction*>?

I think the method layout as is is fine. Makes it fairly close what the code is doing. Though, Neko may disagree with his slightly more agressive stance on lambdas than me.

[twdarkeh]

One request if possible; add a "pin game" to force a single game to stay on the list. Since Disc Games show up on the list, the ability to force them to stay there would be great.

[Megamouse]

I tried but I don't like the outcome.
maybe in the future (possibly with new Qt Stuff at that point)

You can still use the freeze in the meantime

edit: still trying but I won't resist merge