INav: degrade pos error slowly on loss of GPS

When GPS message is late by 100ms or we are glitching, degrade the GPS
vs inertial nav position error to 10% over 2 seconds instead of
immediately setting it to zero.  This avoids jumpy position estimates
when the GPS misses an update
Copter: arming check for gps if GPS FS set to LAND_EVEN_STABILIZE

Setting the GPS Failsafe to LAND_EVEN_STABILIZE means the copter will
LAND if it loses GPS even if it's in a manual flight mode like
Stabilize.  With this setting it makes sense to check the GPS quality
before arming even if we're in stabilize mode.
TradHeli: remove slash from parameter description

This may fix the issue in which the parameter descriptions are appearing
twice on the arducopter-parameters wiki page
Copter: fix SingleCopter motor parameters link
Copter: prefix SingleCopter's MOT param description

This should allow single copter's MOT_ parameter descriptions to be more
easily recognised as belonging to SingleCopter when viewed on the wiki's
arducopter-parameters page
Copter: increase min LAND_SPEED to 30cm/s
Ublox: update config to ver 7.03
Ublox: disable TimePulse Timedata in 3DR config
Ublox: set default rate to 5hz in 3DR config
Ublox: disable NMEA info in 3DR config
INav: record error_count when GPS msg is late
Copter: add INAV error count to PM dataflash msg
Copter: pre-arm check that INAV has no errors
Copter: AC3.1-rc7 version and release notes
Copter: revert pre-arm check for slow GPS
Copter: update -rc7 release notes
Copter: commit to kick-off auto rebuild for -rc7 release
Copter: log GPS messages even when no fix
Copter: remove unused gps_fix_count
GCS_MAVLink: increase max packet size to 104

this enables the DATA96 packet to be sent