… switch state

This LUA script is an evolution on the MissionSelector.LUA.
Allows you to select up to 10 missions, either while arming or in the unarmed state.
Requires that an RC_xFUNCTION be set to 24 (Mission Reset).
The scripts should be installed in the SCRIPTS folder on the MicroSD, and the mission files in the root.
The mission file called mission0.txt (the default mission) must exist and is loaded at boot, if the script does not find it it stops working.
To load to the next mission file just bring AUX switch from low to high, each switch loads the next mission file in numerical order.
If the next mission file numerically does not exist load the next one, at the end of the rotation it returns to load mission0.txt.
Provides for sending messages under any condition, load or error.

Fix typo

Changed the operating logic:

- always loads mission0.txt at startup, cycles missions to AUX high if held for less than 3 seconds
- resets mission0.txt if AUX is high for more than 3 seconds

Cosmetic

Updated operating logic

- removal of last_sw_pos
- removed all comments except the initial ones

Inhibited the ability to change mission if flight mode is AUTO, with associated warning message

If a mission switch is attempted in AUTO flight mode, a warning “Could not clear current mission” will be shown and no operation will be performed.

Fixed issue that sent duplicate mission change messages.

Second attempt: fixed duplicate message sending problem in mission loading.