Refactored RC control for GPIO pins (#860)

* WIP

* Fixed web server

* Got the basics woprking

* Fixed some logic, trapped some error conditions

Also changed "SERVO_ESC" drivetrain type, which doesn't really mean anything, to "I2C_SERVO", which actually describes the board used

* removed RC class stub

* Basic port done

* cleanup

* Fixed mode switch

* Fixed joystick import issue

* Changed option name to "PIGPIO_RC" which is more clear

* changed rc controller option config to "pigpio_rc"

* typo

* Fixed comment to align with nomenclature

* Fixed auto-record on throttle

Did a little other cleanup

* Cosmetic cleanup per review

* Fixed auto-record so it is only on when desired

Did some other cleanup of unneeded constants and added a debug option

* Changes per review

* WIP

Fixed web server

Got the basics woprking

Fixed some logic, trapped some error conditions

Also changed "SERVO_ESC" drivetrain type, which doesn't really mean anything, to "I2C_SERVO", which actually describes the board used

removed RC class stub

Basic port done

cleanup

Fixed mode switch

Fixed joystick import issue

Changed option name to "PIGPIO_RC" which is more clear

changed rc controller option config to "pigpio_rc"

typo

Fixed comment to align with nomenclature

Fixed auto-record on throttle

Did a little other cleanup

Cosmetic cleanup per review

Fixed auto-record so it is only on when desired

Did some other cleanup of unneeded constants and added a debug option

Changes per review

* Addressed code review

Co-authored-by: Chris Anderson <gca2@earthlink.net>