Changed relevant occurences of margin with "anchor offset" or "offset".
Also reworded paragraph about aspect ratios, as it included information that may not necessarily be correct.
Also replaced images with newer versions.
This reduces the size of ZIP downloads for offline reading.
Unused images were found by running `_tools/list-unused-images.sh`.
These images were used in Godot 2.x and 3.x documentation,
but have been replaced by remade images with different names since.
- Update screenshots for Godot 4.0.
- Document RichTextLabel having its own vertical scrollbar.
- Document `push_[tag]()` and `pop()` functions as a faster alternative
to BBCode.
- Document threading support and when to use it.
- Document how to escape user input to prevent it from having its
BBCode tags parsed.
- Document stripping BBCode tags from the text.
- Mention entangled tags not being supported.
- Mention faux bold/italic versus real bold/italic fonts.
- Document `[hint]` and `[dropcap]` BBCode tags.
- Mention animated RichTextEffects pausing when the scene tree is paused
and how to control this behavior.
- Modify RichTextEffect examples to use the actual default values.
- Add screenshot showcasing how to add a RichTextEffect to the
Custom Effects inspector property.
- Fix and improve `[pulse]` custom RichTextEffect. This adds an easing parameter
and makes the target color a multiplier, so that colored text keeps its original
color while fading in and out.
- Mention subpixel positioning should be disabled for fonts with a pixel art
appearance.
- Update bitmap font import dock image and document image/character margin.
- Fixed character range example to match the font image (it previously
had to be reduced by 1 due to an off-by-one error in the importer code).
