Dynamic Sketch

[Robadob]

A while back I added the ability to add line sketches to visualisations, this has mostly been used to visualise the environment boundaries.

e.g.: https://github.com/FLAMEGPU/FLAMEGPU2/blob/51bb37f321c5691d59deff80bd1fd77dbc3bbe05/examples/circles_spatial3D/src/main.cu#L138

The model Carlos is working on, has dynamic boundaries which change with the model. He's currently using some fake agents, to mark the corners of the boundaries.

It would make sense to allow sketches to be added/removed, from the HostAPI. This might not be too difficult, it would just mean updating existing sketch to allow names to be set (similar to how SDL_EXP sketches work: https://github.com/Robadob/sdl_exp/blob/a40d4cae105933d7baa06a02c3f588938a8ef379/sdl_exp/visualisation/Draw.h#L51).

Offtopic: This could also open the way for dynamic display of env vars.