New french regulations imacting ground stations

#### Issue details
Hi everybody,

Some new laws will appears in France in July .

One of them concerns the ground station.
This new law implies that the maximum flight altitude option could not be disabled and if you set a value more than 150m a warning message should appears.

I put you the "decret" and "arrete" in fench, if you are interrested by the subject.
https://old2017.federation-drone.org/wp-content/uploads/2015/01/5-Decret-limitation-capacite%CC%81-V03-08-2017.pdf

https://old2017.federation-drone.org/wp-content/uploads/2015/01/6-Arrete-limitation-de-capacite%CC%81-V03-08-2017.pdf

But I think the problem is more global.
Country specific laws should appears in a lot of country.
What is the better solution to implement them

Create a fork for each country?
Implement them in master branch and activate them depending of your location?
Thanks
#### Version
ALL

#### Platform
[ ] All
[ ] AntennaTracker
[ X] Copter
[ X] Plane
[ ] Rover
[ ] Sub

#### Airframe type
ALL
#### Hardware type
ALL
#### Logs

Start by reading the linked French decree and order, then compare their requirements with the issue’s requested ground-station behavior: the maximum altitude option must remain enabled, and values above 150 m should trigger a warning. The issue asks how country-specific rules should be implemented, so a solution would need to establish that approach and determine how the requested behavior fits it.

Written by the indexing model from the issue text.