Correctly report issue if a required asset is not available;  Fix issue loading a colormap for the gaia stars

* Fix for rendering DoublePropertys in ImGui
* Adding an ImageSequenceTileProvider that loads a folder of images and makes them available through a user-selectable index

* Adapt to explicit specifcation of texture size

Feature/multiple joysticks

General overhaul of the Asset loading system

# Conflicts:
#	src/navigation/pathcurves/avoidcollisioncurve.cpp

Fixes "bouncing motion" that sometime happened when going to a position that is close to the original position

And update some tests based on the change

Includes fix for broken touch gui

Fix an issue where the removal of a screenspacerenderable is published after the screenspace renderable has already been destroyed

* Python script to download all the columns needed
* Update task file. Use strings instead of std::filesystem::path, so that relative paths and tokens can be used