Added configuration options for initial repeat delay and delay between repetitions if IR commands for USB-UIRT.
Basic code cleanup of USBUIRT.cs bringing it to current standards as well as loading the new parameters.
Added the configurable initial repeat delay and delay between repeats to USBUIRT.cs
For input of numbers the initial repeat delay will be used between repeats to avoid SMS style input being to fast.
Changing RenderButton() of GUIListControl.cs to make use of unfocusedAlpha again.

We might deal here with an unfinished implementation of alpha blending textures as the RederButton() function uses a variable _diffuseColor of its parent class.

This variable is changed by the Opacity() method of the parent class. But never gets called anywhere in the code base.

It's possible that other classes are also affected. This is an initial fix for testing if RenderButton() is the actual problem.
Merge branch 'refs/heads/BUG-4118-Add_Padding_Property_To_Labels' into BUG-4187-UnfocusedAlpha_and_textures_in_ListControl
Combined diffuseColor and unfocusedAlpha usage in GUIListControl.cs for textues.
Merge branch 'refs/heads/master' into BUG-4076-USB-UIRT_repeats_commands_too_slow

Conflicts:
	mediaportal/Configuration/MediaPortal.Configuration.csproj
Merge branch 'refs/heads/BUG-4076-USB-UIRT_repeats_commands_too_slow'
Merge branch 'refs/heads/BUG-4187-UnfocusedAlpha_and_textures_in_ListControl'