Some UI tweaks

Fixed tab order in region-login-dialogue.
Added IsCancel to cancel-button in region-login-dialogue. Now cancels
editing if escape is pressed.
Added ability to double-click in the RegionGrid to start editing
region-login.
Added start-as-minimized-option. Moved RiotControl-specific options out of RiotGear.

Added RiotControl.RiotControlConfiguration class which inherits from
RiotGear.Configuration and moved RiotControl-specific options out of
RiotGear.
Merge pull request #83 from DrInfiniteExplorer/master

Start minimized and UI-tweaks