Bug fix to the AB Centre feature

veriTrak is now delivered through NTRIP rather than MQTT

Changes:
• RTK corrections now use NTRIP instead of MQTT

Fixes:
• Coverage only partly redrawing after restarting the app
• Work recorded just before closing the app being lost
• Map coverage breaking into overlapping strips
• Guide lines not returning to where you left them
• The selected line jumping between lines while driving
• Lines not following you across the field
• LED guidance flickering after restarting
• Centring moving only the lines, not the guidance