* KDE theme: fix visual problems with KDE dark mode; add system theme
* Make "Light" theme truly light under Breeze Dark theme.
* With this fix also expose dark mode support on Windows.
* Add "Auto" (system) theme that follows system style and color.
* Add "Adaptive" color scheme for system theme (using transparent background).
* Add support for transparent background in color schemes.
* move `alphaBlend` to utils
* hide Auto (system) theme on Windows
- change: Don't auto disable compile and debug buttons.
- enhancement: Better error messages for missing compile/debug/make programs.
- enhancement: "Show special chars" in options / editor / font
- fix: Lost compiler set settings if a compiler set's bin dirs is empty.
- enhancement: Better error message when trying to debug with Release compile set.
- enhancement: can use different colors to highlight the current word and the selections
- enhancement: can set editor's default background / foreground color. They must be setted to make the custom color schemes correctly.
- enhancement: can set the color for the current line's number in the gutter
- all predefined color schemes updated.
- fix: Custom color settings not correctly displayed in the options widget
- enhancement: add hit counts in the search result view
- fix: editor actions' state not correctly updated after close editors.
- fix: When replace in the editor, "Yes to All" and "No" button doesn't work correctly.
- fix: crash when editing non-c/c++ files
- enhancement: set the alpha value of scheme colors
- enhancement: can use symbols' own scheme color to draw selection
- enhancement: can use different colors to highlight the current word and the selections