CEmu: all versions and old releases

After many years and around 450 commits, it's finally here... CEmu is more accurate and more powerful than ever before :)
Core:
- Support for real host->emu transfers (USB emulation), by @jacobly0. i.e. you can now transfer Apps and OSes normally
- Support for rev M+ hardware (excluding Python coprocessor), by @jacobly0 and @calc84maniac.
- Major LCD emulation improvements, by @calc84maniac.
- Major watchdog timer rewrite based on hardware research, by @calc84maniac.
- Prepare future Python-related features, by @jacobly0 and @calc84maniac (SPI, UART...)
- Big endian support, by @calc84maniac
- Make keypress emulation thread-safe, by @calc84maniac
- Lots of other misc. fixes and improvements (timing, accuracy, performance, rst/trap edge cases...)
GUI:
- Proper dark mode support (be sure to use Qt6 builds)
- Improved display of emulation speed and screen refresh rate
- Screenshots/recordings now have correct screen brightness
- Fix fullscreen mode when using multiple monitors
- Add upscale method and fullscreen aspect ratio settings
- Add vertical printing to Keypress History
- Add calculator skins for newer models, and some new color variants
- Add some debugging features for TI-Basic (step-by-step execution, live variable preview etc.)
- Fix name of a few OS variables in some cases (some were labeled Ans, formula lists support...)
- Fix crash upon trying to export natural keymap (you can't)
- Fix byte display order in disassembler for index bit instructions
- Fix R register in debugger.
- Deduplicate imported equates in the debugger
- Add/improve variable content preview (tivars_lib_cpp updates)
- Add disassembler option for tabs between the opcode and operands
- Fix "Pause emulation" preventing CEmu from closing
- Add SmartPad keymap (for use with the calc app)
- Add screenshot IPC command/option
- macOS: fix screenshot drag'n'drop
- Add --reset CLI option to clear the config
- New/improved translations by @Stephan-P (NL), @wolfarmoon (ES), @Jerry23011+@LifeEmu (CN)
- Better version update check
- Lots of various fixes
CI / Build:
@calc84maniac and @adriweb have been improving the build system and CI workflows:
- Move the CI to GitHub actions (now provide builds for all three OSes)
- macOS: native builds available for both Intel and Apple Silicon
- macOS: the builds are now codesigned and notarized automatically
- Take care of some LTO issues
- Update to latest Qt5 and Qt6
- CMake support (with vcpkg integration)
TI-Basic debugging live variable view basic debugging
❤️ We thank all of our contributors, and you, users, as well - Enjoy the new release!