Tracking Wine fixes

[FenPhoenix]

NOTE! Wine fixes are best-effort; these are Wine bugs, not AngelLoader bugs per se, and I may not be able to work around all of them.

Issues found so far:

• [x] Unicode pin character is rendered as missing glyphs (may be a broader font issue)
• [x] Some icons look garbled
  • Fixed by installing gdiplus through winetricks
• [x] RTF readmes don't display images
  • Fixed by installing msftedit through winetricks, which also requires msls31.dll (32-bit can be obtained through winetricks msls31 package; 64-bit must be obtained manually)
• [x] msftedit crashes on many non-ASCII chars
  • fixed by installing msls31.dll
• [x] RTF readmes don't accept the background color for dark mode, meaning their background remains light while text is also light, making it difficult/impossible to read
• [x] Scroll bar controls (as in, not native Windows ones that are attached to native controls, but standalone managed VScrollBar/HScrollBar WinForms controls only) don't respond to hooked theming for the bar portion, which shows up as light colored still
• [x] DateTimePicker background color remains light
• [x] Readme chooser ComboBox closes before the user can select anything (really fixed this time)
• [x] Horizontal lines are drawn in the slightly wrong vertical location in Appearance tab (like a text-line's height too high)
• [x] Progress bars aren't properly themed in dark mode
• [x] Somehow make it so the winetricks dependencies (gdiplus and msftedit) can be installed, or ask the user to install, or just somehow let the user know they should install them
• [x] About window text is mispositioned
• [x] Multi-choice item list dialog has bottom text positioned on the right and squished all weird
• [x] Ah, the infamous undocumented scroll bar corner id... it doesn't work. White scroll bar corners between horiz and vert
• [x] With the default Wine Mono, many codepages aren't supported and cause a crash when accessed. This could be fixed by installing dotnet472 through winetricks, but we've fixed it on our side by simply including the System.Text.Encoding.Codepages dependency, which saves users a large amount of time and hassle.