LibCECTray updates and fixes

Added ability to send modifiers by nesting commands in KeyInput.cs

Made it so that if you click the first column in the WMC grid view. It'll send the command to the open app.

Fixed bug with libcec adding the keyup for button commands and making sure they are still executed.
Merge pull request #117 from n8o/master

LibCECTray updates and fixes