Added prompt to enable/disable local echo and additional modifications:
* Added prompt to enable/disable local echo during UART passthrough
* Added CharInNoEcho object to Parallax Serial Terminal.spin
* Added URL for Parallax support in VersionInfo string
* Moved input string buffer (vCmd) to be a global variable
* Renamed Parallax Serial Terminal.spin to PropSerial.spin
Updated copyright dates
Updated for FW version 1.2.1