* 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
- Ability to enable and disable rules in various loops
- Simplified code overall
- Port forwarding moved into openvpn loop
- Route addition and removal improved
- Fix bad permissions bits for files
- VPNSP is 'private internet access' instead of 'pia' (retro compatible)
- Check errors of deferred unsetEnv functions in params package
- Other lint errors fixing and code simplifications
- Obtains VPN public IP address from routing table
- Logs and writes VPN Public IP address to `/ip` as soon as VPN is up
- Obtain port forward, logs it and writes it as soon as VPN is up
- Routing fully refactored and tested
- Routing reads from `/proc/net/route`
- Routing mutates the routes using `ip route ...`