ENH: Add support for virtual keyboard and numpad

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.

qtpyvcp/app/application.py

@@ -19,6 +19,7 @@
 from qtpyvcp.plugins import initialisePlugins, terminatePlugins, getPlugin
 from qtpyvcp.widgets.base_widgets.base_widget import VCPPrimitiveWidget
 from qtpyvcp.widgets.form_widgets.main_window import VCPMainWindow
+from qtpyvcp.widgets.virtual_input.virtual_input import VirtualInput
 
 # initialize logging. If a base logger was already initialized in a startup
 # script (e.g. vcp_launcher.py), then that logger will be returned, otherwise
@@ -44,6 +45,8 @@ def __init__(self, theme=None, stylesheet=None, custom_fonts=[]):
 
         self.status = getPlugin('status')
 
+        VirtualInput.try_enable_virtual_input(self)
+
         # initialize plugins
         initialisePlugins()