ENH: Add support for virtual keyboard and numpad

[adargel]

Problem:

• Touchscreen users had no app specific onscreen input methods.

Solution:

• Add a virtual numpad and keyboard and show them for editable fields when TOUCHSCREEN is found in the display section and it is set to True, 1, or yes.

• Show the numpad when the field is numeric, else show the full keyboard.

• The input panel is placed below the control it is editing, unless any part of the panel would be offscreen. In which case, the panel will be positioned as closely to the control as possible without running offscreen.

[adargel]

[KurtJacobson]

@adargel I made a few changes so that individual VCPs can override the default Virtual Inputs used via the plugin system. I also changed to using a setting for whether to show the virtual inputs or not rather than an INI setting so it can be changed on the fly from the GUI.

Can you please test and verify I did not break anything?

Thank you for the excellent PR, and sorry for not being able to keep my paws off it!

[adargel]

Looks good to me. No worries on changing my code, that is expected and excellent.