Fix formula to consider Bandwidth in kHz

Updated the frequency selection formula

Allow range test module to loop back messages

fix comments in smart position

Allow up to 500mW transmission power for EU868 region

Removed comment about frequency hopping due to lack of universal hardware support

The European Union regulations clearly state that the power limit for this frequency range is 500 mW, or 27 dBm. goTenna Mesh uses the same frequency range and power limit too.

It also states that we can use interference avoidance and spectrum access techniques to avoid a duty cycle.

It might be worthwhile in the future to implement frequency hopping to avoid duty cycling.

(Please refer to page 69 in the following document)
        https://ec.europa.eu/growth/tools-databases/tris/index.cfm/ro/search/?trisaction=search.detail&year=2021&num=528&dLang=EN

* Set last gps coordinates after comparison

* Wrong spot

Add ability to adjust frequency by config.lora.frequency_offset

* Add voltage + current measurements

* mA instead of amp

* Node db cleanup and debug prints

* File name cleanup

Adding clarification to comments on GeoCoord::bearing function.

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

Fix returning pointer to local variable that will become invalid when returning.

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

Co-authored-by: thebentern <thebentern@users.noreply.github.com>

avoid BLE device names like a123_a123

Small fixes and inprovements

- non-zero config.lora.bandwidth means a custom radio config, not 'Unknown'
- Enable 'this is a new device, set region' screen again now we can actually set region.