Add support for background-repeat, background-size needs fixing

Add support for background-position.

Implement background-origin!

Implement conic gradients, support elliptical extents.

Parse radial gradient extents, slightly differs for circles vs ellipse.

Minor legibility & theoretical-performance optimizations.

Use forward-unrolled loop to lookup the transition to apply, avoiding else-if branches.
Use GL_TRIANGLE_STRIP to avoid the need to upload duplicate vertex data.

Parse radial gradient center-position.

Add support for circular gradients, prepare shaders to allow setting center.

Add simple radial gradient support, fix lint warnings.

Allow configuring where colour stops occur.

Add support for colour stops, equally spaced.

10 stops should be generous!

Add angular linear gradient support!

Add basic support for linear gradients!

Test whether colour conversion is giving me the issues on certain JPGs, nope!

Implement background-size!

Fix coordinatespace for texture-pixel lookup.

Constrain textures to limited commonly-supported colourspaces.

Fix parsing of background-image, attempt to fix image rendering.

Build texturing infrastructure & implement background-color!

Commit missing Image module.