[UI] Add settings print for text settings as well as helper to print a save button for individual text settings.
[scripts] Add a couple fixes for running scripts

• Allow overriding CFGFILE variable when running scripts... likely more
  to follow.

• Allow spaces in arguments being passed to eventScript
[fppd settings] Updates to helper, and remove hard coded path

• Store the fppDirectory and add a getter

• Invoke eventScript wrapper via the configured path instead
  of hard-coded location in /opt/fpp
[UI] Fix variable check on PrintSettingSelect helper
[plugins] Fixes & updates for plugin support

• Call plugin scripts through our eventScript wrapper for a couple of
  reasons:
    · We can now call them if they're not executable (i.e. they're on a
      FAT32 filesystem)
    · If we make any changes to environment variables or anything, they
      will be done across the board with only updates to one location

• Remove a couple debug prints accidentally left in during plugin
  development.

• Fix JSON formatting for different playlist entry types for the data we
  pass to the plugins for playlist start/stop.

• Only call the PlaylistCallback once when stopping.
[plugins] Add SHA to stored variables.

This now pins to a specific revision.  This will allow us to have
different revisions of the plugin on different branches of FPP.  When
developing new plugin features that require changes within FPP as well
as within the plugin itself, this feature may be needed.
[wxWidgets] Add makefile for building wxWidgets

For the current fppconvert code, we need to compile wxWidgets for the
helpers used in xLights (which we use).  This Makefile will download,
configure, and build wxWidgets appropriately on a Pi.