- Download working again
- Fixed lots of bad error handling

writeFileAccumulator contents cleared on errors, nack or ack timeout
memcpy used to transfer data to request message buffer

QGCUASParamManager and friends are replaced by FactSystem

When you load a waypoint files, the changes you're doing in the waypoint list
(for example, changing the longitude of a waypoint) are not applied to the points
displayed on the map.
This commit fixes this issue.

New version using QtQuick along with an experimental Map Background

Link ids were being used interchangeably with the mavlink channel for
the link. Link ids handed out as a numerically increasing integer. Once
the counter went past MAVLINK_COMM_NUM_BUFFERS all hell would break
loose and cause memory corruption.

Also removed partially implemented an incorrect getCommunicationStatus
api

Also many LinkManager API changes to further isolate all link
management inside LinkManager.

So this special casing is no longer needed

If it doesn’t exist it will be prefilled with all registered categories
set to false

Otherwise some messages say 'System MAV 0-20' and some say 'System 20'.