GPS fixes and GPS soft serial support

Added possibility to use both Serial RX (Spektrum satellite/SBUS/SUMD)
and GPS at the same time.
- When features: feature SERIALRX, feature SOFTSERIAL and feature GPS
are enabled Serial RX is using UART and pins 3&4 and GPS is using soft
serial and pins 5&6.
- Fixed GPS code, so that now it's reconnecting if connection to GPS is
lost.
- GPS tab on Chrome Configurator now shows GPS signal strength.
- Possibility to disable SBAS (ground assistace type). (SBAS causes
occasional severe altitude calcuation errors)
Revert "Formatting correction"

This reverts commit e14e5ce503a0d8cec4154a2cf2297e7dd81981fb.
Revert "Spektrum satellite binding improvement"

This reverts commit 2466db4b47ddbc734f1be3d4eadfd85d4e2cd0a6.