No major functionality changes.

Fix unit test crash rom Pull 840

Fix Linux compiler warnings from Pull 840

Updated RC Cal validation rules

Also uses new min/max/invalid widget display

handle wgs84 altitude correctly, AMSL also displayed in ft

RC Calibration Updates

emit roll, pitch and yaw setpoints for plotting

also adds AMSL output in ft

- Updated to use RCChannelWidget
- Removed attitude control widgets
- Previous calibration values now shown when not actively calibrating

Left QGCRadioChannelDisplay alone so that I didn’t need to modify all
the other APM board code which uses this control. Also new control only
support horizontal orientation, with no plans to add vertical.

Threading fixes

Path through code allowed for xmlfile to be used when file was not
opened. Also changed qWarning->qDebug to allow QT_FAIL_WARNINGS to be
used to find bugs.

This allows us to run with QT_FAIL_WARNINGS to find bugs. Also temp
comment out of failed signal connection.

This prevents a threading problem where previously the new happened on
the wrong thread.

This way we can test with QT_FAIL_WARNINGS set.

Need to check for QImage failure otherwise it will through a qWarning.

mavlink: updated submode to latest master

New implementation of PX4 RC Calibration