remove MavSDK from cmake and add small documentation file

updated .gitignore

Fix pico flexx tcp connection

connecting to tcp seems to work much more consistent now. It only needs about 3 tries instead of 30+

Add support of RealSense SDK 2.0

Implement IdleImageSourceEngine - READY FOR REVIEW

remove early outs in the prepare for tracking method

Revert "remove early outs in the prepare for tracking method, since they were preventing the update of the live render state, thus breaking the freespace carving for sequences tracked from disk"

This reverts commit 08826527.

remove early outs in the prepare for tracking method, since they were preventing the update of the live render state, thus breaking the freespace carving for sequences tracked from disk

Add a field in the TrackingState to store a score computed by the tracker.

`InputSource::RealSense2Engine` requests two streams from the first available device:
- 16 bits depth buffer
- 32 bits rgba8 color stream

Then it calibrate infiniTAM by fetching:
- depth sensor scale
- projection of depth and rgb sensor (intrinsic)
- affine transform from rgb to depth sensor (extrinsics)

allow the serialisation/deserialisation of images

the MEMORYDEVICE_CUDA variant was already doing it whilst the CPU version was throwing. now the behaviour is consistent

allow the file-based tracker to start tracking from a specified frame index

Add ITMIntrinsics::MakeRescaled - READY FOR REVIEW