Also added Center to Mission support

Also additional major Mission usability changes

- Positions are bounded to rectangle
- No longer re-centers if thumbs go outside bounds
- ThumbPad moves to meet first thumb position, this prevents
inadvertent movement as you put your thumb down

Add scroll height indicators to Flickable

This reverts commit bf31c808.

The overloaded member signal just hit us, to use it is a pain
but the resuting code is faster and less error prone, so it's
still a good thing to do.
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

Causes UI to hang up

Hamburger: Delete, Delete All, Show all Values

Hamburger: Delete, Delete All, Show all Values

Total hack but it seems to work

There are many ways of iterating over lists in C++/Qt.
In the specific case of QStrings, it is known [1] that using
foreach with const references avoids the creation of new
QString objects in each iteration, reducing the time consumed
by the loops.

[1] https://blog.qt.io/blog/2009/01/23/iterating-efficiently/Signed-off-by: Anselmo L. S. Melo <anselmo.melo@intel.com>

This commit introduces the APM Airframe configuration. The interface
is the same as the PX4 one, but the way we deal with the uas is a bit different

Since the APM stack doesn't provide a xml with airframe definitions a
new one was created by hand with only the values that we need, wich will
trigger a download of the parameters file from the mavlink github

Now it correctly handles the FRAME variable and it's faster
regarding the download of the parameters for each type of Frame.

Only show Airframes for ArduCopter, not for ArduRover nor ArduPlane
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>