Add Global and Local rotation spaces

[InvixGG]

Adds Global and Local rotation to the viewport tools. The existing Euler-channel behavior is named Gimbal and remains the default.

Adapted from Mine-imator Vexel Build (MI VB), originally introduced in Vexel-Studios/vexel-mine-imator#111.

The button below the viewport toolbar cycles between the three spaces, as does the remappable Q shortcut. Each space has its own icon and ring colors. Local uses the active object's axes when several objects are selected.

The choice is saved in program settings. Project files and animation curves still use Euler rotations, and changing the space does not edit keyframes or add an undo step.

Compatibility

• Based on 2.1, alongside the rendering work in Mine-imator 2.1 rendering (WIP) #45.
• IK, path-following objects, inherited poses, locked selections, and selected rotation keys away from the current frame keep Gimbal behavior. The tooltip explains when this applies.
• Zero, negative, or nonuniform object scales and stretched, sheared, or mirrored parent transforms also keep Gimbal behavior.
• Global and Local preserve complete turns during a drag and account for parents whose position inheritance is disabled.
• Includes a small undo fix: removing a newly created transform key must not restore its values into the following key.

[mbandersmc]

Strongly recommend having the other view controls be affected by this too, not just rotation.

MI/Blender example:

[InvixGG]

Strongly recommend having the other view controls be affected by this too, not just rotation.

Sounds good, will take a look at this and get that added.

[InvixGG]

@mbandersmc Added this in 170afd2. Move and Scale now follow the selected Global/Local orientation too, including the combined transform tool. Local uses the active object's axes, and nested selections account for their parent transforms without applying the inherited transform twice.

Also fixed a crash when dragging objects between parents in the timeline. The gizmo now keeps using the original parent until the drop completes.

Scale keeps the existing rotation values, so stretches that would require shear are approximated using the XYZ scale channels. Gimbal keeps its previous behavior.

[NimiSqrd]

Got around to checking this out, thanks for putting time into this PR. It seems fine in C++ but there's some issues on the GameMaker side and code consistency.

Some issues and suggestions:

• GML side uses GameMaker keywords like x/y, causing some compile/runtime issues. Since this feature doesn't require anything special from C++, 1:1 behavior is ideal.
• Functions usually get their own script with JSdoc headers, the current convention in the GML codebase.
• Some wording seems complex for newer users, I'd do a pass over naming and opt for something like "transform_mode", "Gimbal mode" in the UI, etc.
• There seems to be a lot of state management and duplication(?) with view_control_transform_* and view_control_rotation_*, some simplification would be nice if possible.
• A lot of the code styling seems compact, making it a little spacious like the rest of the code would be nice.

btw there is a feature-freeze approaching in a couple days for 2.1. If addressing these would require a large refactor, don’t feel pressured to invest more time just to squeeze it in.