Remove unreferenced & undocumented class scene/resources/Space2D

Added has_signal method for Object

Adding missing include guards to header files identified by LGTM

This addresses the issue godotengine/godot#37143

Implement Sky Shaders

Fix warning: Property not found: mono/editor/editor_path_optional 

Make file formatting comply with POSIX standards

Travis CI has had trouble the past few days and macOS builds error out
for no reason.

UTF-8, LF, no BOM, and newlines at the end of files

Fixes transform gizmo position when node has default transform

Fix potential divisions by 0 reported by MSVC

Changes made:
* Added dirty bit for SpatialEditorSelectedItem's last_xform
* SpatialEditorViewport checks that dirt bit too before skipping the selection

The `TextEdit` one was indeed a potential bug.
The `PCKPacker` one seems to be a false positive, it's already in a
`for` loop that depends on `files.size()`.

Fix incorrect shader block parsing

Allow to reassign local variables in shaders

i18n: Improve classref translation extractor, add Makefile and generate .pot file

Change extract script `path` argument to support specifying multiple
paths, like `makerst.py`. This prevents parsing invalid XML files while
scanning the whole repository.

i18n: Add support for translating the class reference

Fixes navigation path reset

Add script to generate translation catalog for the class reference

Update the naming scheme for the GodotPlugin's methods

See https://github.com/godotengine/godot/pull/37114#issuecomment-601463765

- Parse `.po` files from `doc/translations/*.po` like already done
  with `editor/translations/*.po`.
- Add logic to register a doc translation mapping in `TranslationServer`
  and `EditorSettings`.
- Add `DTR()` to lookup the doc translation mapping (similar to `TTR()`).
  Strings are automatically dedented and stripped of whitespace to ensure
  that they would match the translation catalog.
- Use `DTR()` to translate relevant strings in `EditorHelp`,
  `EditorInspector`, `CreateDialog`, `ConnectionsDialog`.
- Small simplification to `TranslationLoaderPO`, the path argument was
  not really meaningful.

Fix shader TIME auto-completion

Removed old TIME references from shader_types

Fix editor crash when stopping game with F8.

Makes shader 'TIME' available in custom functions by default