This branch seems pretty stable, and it lets us get rid of some
legacy code about extensions.

imGui docking extension tweak
tileset new getters

small imgui extension
scene palette shader crashfix

- removed 0 CR characters
 - removed 7 trailing whitespaces
 - replaced 332 tabs with spaces

Reworked Primitive logic for scene rendering
FileUpdateTester works now .....

MeshViewer first pass

SDL2: Mouse is back ! With correct focus support
SDL2: Added typing support with keyboard
ShaderBuilder: Refactored and simplified Shader block creation
Several warning removal
Fixed Image::Copy

Added Texture (by image) update in TextureImage (and tileset)
Added lolimgui first integration pass