Fixes most current reports on Coverity Scan of uninitialized scalar
variable (CWE-457): https://cwe.mitre.org/data/definitions/457.html
These happen most of the time (in our code) when instanciating structs
without a constructor (or with an incomplete one), and later returning
the instance. This is sometimes intended though, as some parameters are
only used in some situations and should not be double-initialized for
performance reasons (e.g. `constant` in ShaderLanguage::Token).
It seems that popups were intended to "grab" the mouse click that triggered them, but their intent was being lost. This commit does the necessary changes to let it happen and updates items that were trying to get advantage of it, because the semantics of `Control::grab_click_focus()` have changed a bit. Namely, it must be called **before** showing the modal.
This allows to popup a menu and activate an item in it in a single click-point-release cycle, instead of having to click once to open the menu and once more to pick an item.
This ability is extended even to context menus activated with the RMB (or any other mouse button, for that matter). The editor benefits from this in the context menu of the tree dock, which has been patched to opt-in for this feature.
This improves UX a bit by saving unnecessary clicks.
From now on, `PopupMenu` always grabs the click and also invalidates the first button release unless the mouse has moved (that's what `set_invalidate_click_until_motion()` was doing and now it's removed), so there is no longer the need of doing both things at every point a pop-up menu is shown.
Found via `codespell -q 3 --skip="./thirdparty,./editor/translations" -I ../godot-word-whitelist.txt`
Whitelist consists of:
```
ang
doubleclick
lod
nd
que
te
unselect
```
- The input handling is done into several distinct functions, and the
code is more consistent.
- The actions' history is more precise ("Edited CanvasItem"
is now "Rotated CanvasItem","Moved CanvasItem",etc...)
- Fixed a little bug about input key events not forwarded correctly to plugins
- IK is followed by default when you move a bone node, the alt-key allow
you to move it normally
- New: Allows for multiple files to be dragged over
- Added error when multiple nodes are dropped in scene **without** scene root
- Removed TTR: "This operation requires a single selected node.", "I see.."
- Introduces TTR: "Can not instaniate multiple nodes without root."
- Fixes "Can't add_child, already got a parent" error
- Reduced multiple resource loading by casting
- Make sure to not _show_resource_type_selector if only PackedScenes are being dropped
Using `misc/scripts/fix_headers.py` on all Godot files.
Some missing header guards were added, and the header inclusion order
was fixed in the Bullet module.
