Survey bounding rect intersection fix

README.md: Add new gstreamer example

Polygon: Create circular polygon

Structure scan: Photo count working, initial vehicle yaw support

PlanView: Solve KML error

Fix #5812
Show an error message when creating a KML without 2 items at least

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Specify altitude for guided takeoff

Structure Scan persistence and mission creation

Move plan view index control to MissionController

New CameraCalc reusable code for complex items

Converted Structure Scan to use CameraCalc such that it now works with
camera specs.

The ball pattern do not work in all cases, this new example add the basic video input with size information.

Bugfix current monitor pin selection indexModel in APM power setup

Stable merge

Linux: Add missing XML lib

Fix battery announce for battery change

APMParameterFact: Solve typo in BATT2_VOLT_MULT description

Change from BATT_VOLT_PIN to BATT2_VOLT_PIN.

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>