Add variables for TX Freq (t30), RX Freq (t32), CPU Temp (t20), and
Location (t31) to Base MMDVM page. These variables are available with
Layout ON7LDS L3 or higher. This allows more dynamic info to be
displayed without having to use the optional NextionDriver. Note, this
doesn't add touch support. For that, use the NextionDriver.
Fixed command mangling occuring during serial writes to Nextion due to
no ready-state monitoring of display readiness. Added simple thread
sleep to pace the commands as they are sent. Allows the display a
chance to process the command before another one is blasted in.
Prevents mangling of commands sent before display is ready to accept
them. Hardwired to 10 msec--let's see if that's enough.
Added setting in mmdvm conf file, Section: [Nextion] Setting:
DisplayTempInFahrenheit Value= 0 (default) for C. 1=Fahrenheit This
controls the value sent to t20.
