This PR and commit adds the functionality to arrange nodes in VisualScript/VisualShader editor. The layout generated by this
feature is compact, with minimum crossings between connections
& uniform horizontal & vertical gaps between the nodes.
This work has been sponsored by GSoC '21.
Full list of additions/changes:
• Added arrange_nodes() method in GraphEdit module.
• This method computes new positions for all the selected
nodes by forming blocks and compressing them.
The nodes are moved to these new positions.
• Adding this method to GraphEdit makes it available for
use in VisualScript/VisualShaders editors and its other
subclasses.
• Button with an icon has been added to call arrange_nodes() in GraphEdit.
• This button is inherited by VisualScript/VisualShaders editors
to invoke the method.
• Undo/redo is functional with this method.
• By using signals in arrange_nodes(), position changes are registered
in undo/redo stack of the subclass that is using the method.
• Metadata of the method has been updated in ClassDB
• Method description has been added to class reference of GraphEdit
Found via `codespell -q 3 -S ./thirdparty,*.po,./DONORS.md -L ackward,ang,ans,ba,beng,cas,childs,childrens,dof,doubleclick,fave,findn,hist,inout,leapyear,lod,nd,numer,ois,ony,paket,seeked,sinc,switchs,te,uint`
* Most resource types now have unique identifiers.
* Applies to text, binary and imported resources.
* File formats reference both by text and UID (when available). UID always has priority.
* Resource UIDs are 64 bits for better compatibility with the engine.
* Can be represented and used textually, example `uuid://dapwmgsmnl28u`.
* A special binary cache file is used and exported, containing the mappings.
Example of how it looks:
```GDScript
[gd_scene load_steps=2 format=3 uid="uid://dw86wq31afig2"]
[ext_resource type="PackedScene" uid="uid://bt36ojelx8q6c" path="res://subscene.scn" id="1_t56hs"]
```
GDScript, shaders and other special resource files can't currently provide UIDs, but this should be doable with special keywords on the files.
This will be reserved for future PRs.
* Friendlier with version control.
* Generates pseudo unique IDs, to minimize conflicts when merging, but still
user readable (so, not UUID).
* Eventually will also allow to have more precisely named sub-resources in
imported files.
* This will allow better reloading on changes (including resources already
loaded) as well as better keeping track of changes on the DCC.
* Keeps backward compatibility with the old formats.
* Binary and text format version incremented to mark breakage in forward
compatibility.
* Create the shader on demand.
* Makes sure compilation happens only once, then shader is cached.
* Speeds up scene loading times.
* Speeds up editor initialization.
