Fixed error when no keyframes to draw (gpu_extras.batch.batch_for_shader does not accept empty list in 3.4).

Fixed warning messages from error in some operator's poll.

Contributed by @xan2622 #blender-coders.

And update dates

Missed in rBA6feb9c532d7b.

Part of T80730

Part of T80730

Part of T80730

The UV color changed after these changes.

This partially reverts commits rBAfdebdd681f0b, rBA563ea27eb1a8 and rBAb56a6acb9f4f.

And fixes T101134.

We still need to find an appropriate way to replace `glEnable(GL_LINE_SMOOTH)`.

The issue was introduced in cf773d42 and vis caused
by a lack of class unregister.

Fixes regression tests, as well as usecase when a user
toggles the addon off and on again.

* Move into its own sub-panel inside the Keyframes panel

* Use column layout for Wireframe Toggle.
* Move into its own sub-panel.

This data-block indicator is no longer needed now that the Node Editor
has a context path overlay introduced in Blender 3.0

Since 2.8 the Shader Editor has a popover with a UIList of all materials,
much more complete than the dropdown implementation in Amaranth.

Good to see Amaranth features being replaced by built-in ones in Blender :D

* AMTH_NODE_OT_show_active_node_image in Node Editor
* AMTH_VIEW3D_OT_render_border_camera in 3D Viewport

FBX exporter code was only supporting "Face Corner - Byte Color"
attribute type, using the deprecated Mesh.vertex_colors API. Update
the to use the new attributes API, and to handle all the attribute
combinations.

An option to pick between sRGB (default, matches current behavior),
Linear (requested in T82847) or None (don't export/import any color
attributes) has been added to the exporter and the importer.

Reviewed By: Bastien Montagne
Differential Revision: https://developer.blender.org/D15942

Part of T80730

Small micro optimization