* Reads the client key from /gluetun/client.key
* Read the client certificate from /gluetun/client.crt
* Additional checks for client key and client certificate validity
* Fix client key file parsing if environment variable isn't present
- Use Windscribe API to fetch servers information
- More data on servers about region, city and hostname
- Add optional server filters with `REGION`, `CITY` and `HOSTNAME` csv environment variables
* Split provider/pia.go in piav3.go and piav4.go
* Change port forwarding signature
* Enable port forwarding parameter for PIA v4
* Fix VPN gateway IP obtention
* Setup HTTP client for TLS with custom cert
* Error message for regions not supporting pf
* Adapt storage: SyncServers write to file option, export FlushToFile
* CLI built-in updater for old and new PIA servers
* Update hardcoded IP addresses for PIA old and new servers
* Add PIA old to allServers struct and update timestamps
* Adapt code to work with new and old PIA servers
* Remove PIA subdomains (unneeded) from resolver tool
- Refers to #218
- Checks for custom port value depending on protocol
- Remove default port from server constants
- Use 443 and 1194 ports respectively for tcp and udp
- Goal was to simplify main.go complexity
- Use common structures and interfaces for all vpn providers
- Moved files around
- Removed some alias models
