A lot of font editor improvements.

[VladiStep]

Description

1. Added the red marker for the selected glyph, made the font texture clickable (closes [REQUEST] Show where GameMaker: Studio will look when searching for a letter #124).
2. Fixed the bug with font texture artifacts (fixes Font texture can be displayed with artifacts. #1319).
3. Made the glyphs table show and accept actual characters (the codes can be seen on hover).
4. The cyan border of the texture page item display can be disabled with the DisplayBorder property.
5. Added the new two buttons - "Edit a selected glyph rectangle" and "Create an empty rectangle".
   The first button opens a window where you can either edit a selected glyph rectangle/area by using mouse or select a rectangle for new glyph (by dragging mouse).
   Also, you can look all glyph rectangles and zoom the texture.
6. Added the "Update range" button that updates the font range start and end values.
7. Added the missing font ascender UI fields.
8. Added the missing documentation for some classes and properties in "UndertaleFont.cs".
9. Added an ability to edit glyph kerning (closes A (better) support for the kerning of a font glyph. #1181).
10. Fixed some DataGrid row related crashes (fixes UTMT crashes on script launch sometimes. #1325).
11. Added the preview for glyph shift and offset values (blinking blue and green lines); added a hint for these grid rows.
12. Added the hint for the tileset editor image and made the cursor "hand".
13. Added the IsVersionAtLeastConverter WPF converter.
14. New fonts have scale of 1.

[github-actions]

Download the artifacts for this pull request here:

GUI:

• GUI-windows-latest-isBundled-false-isSingleFile-false
• GUI-windows-latest-isBundled-false-isSingleFile-true

CLI:

• CLI-macOS-latest-isBundled-false
• CLI-ubuntu-latest-isBundled-false
• CLI-windows-latest-isBundled-false