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
update the active source status correctly after a manual switch to another source. closes #124
cosmetics
added vendor id for Denon
sync with LibCecSharp
rpi: don't try to re-register a logical address when the logical address isn't registered and we receive a VC_CEC_LOGICAL_ADDR_LOST message from the firmware. issue #109
rpi: don't wait for a response (and fail) when opening a connection. issue #109
don't send deck status updates to philips when activating the source
don't send two active source message sequences to philips. issue #118
Add new method PowerOnScreensaver