- Download working again
- Fixed lots of bad error handling

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

Also converted to new logging category

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

Also turn them back on

The goal of this first installment is to organize the code a bit so it's more readable,
clean up a bit of left over cruft, and manage link configurations (and links in general).

- Updated MainWindowTest to catch this problem
- Also implemented initial pass at SetupView unit test

- Updated MainWindowTest to catch this problem
- Also implemented initial pass at SetupView unit test

Changing the order of the QGCFileDialog::getSaveFileName() function. The idea was to expand the existing QFileDialog version but as we removed the selectedFilter, we might as well make this more intuitive. The options argument is the one trully optional and should be last.
Adding an example to the documentation on how to go about figuring out what file type was returned by these functions.