Fix and improve GitHub release actions

[gogins]

• [x] Restructure directories with vst3-opcodes at the top level, along with csound and vst3sdk.
• [x] Change all builds to use the csound submodule. Patch the .h.in files in place. No, use local copies of these files that come first in the include paths.
• [x] On macOS, build the plugins as a universal binary.
• [x] Remove the existing examples and replace them with one better example that has both a VST3 instrument and a VST3 effect, both from free plugins. Not necessary, the existing examples do this and work.
• [x] Include the VST3 SDK example binaries.
• [x] Test fractional MIDI keys. I improved the tuning code, and it looks correct, but the Pianoteq doesn't seem to use it.
• [x] Update the documentation.
• [ ] Fix or remove examples that don't work.
• [x] Ensure all release archives contain the opcodes shared library and examples!

[gogins]

Linux and macOS seem to produce good releases, Windows does not.

[gogins]

michaelgogins@Michaels-MacBook-Pro ~/csound-vst3-opcodes % find vst3sdk -name "*_mac.*" -ls 2>/dev/null  
87797252       32 -rw-r--r--    1 michaelgogins    staff               12709 Dec  8 08:39 vst3sdk/public.sdk/source/vst/hosting/module_mac.mm
87797183        8 -rw-r--r--    1 michaelgogins    staff                3460 Dec  8 08:39 vst3sdk/public.sdk/source/common/systemclipboard_mac.mm
87797187        8 -rw-r--r--    1 michaelgogins    staff                3049 Dec  8 08:39 vst3sdk/public.sdk/source/common/threadchecker_mac.mm
87797768        8 -rw-r--r--    1 michaelgogins    staff                1195 Dec  8 08:39 vst3sdk/vstgui4/vstgui/tests/unittest/lib/platform_helper_mac.mm
27280639        8 -rw-r--r--    1 michaelgogins    staff                 583 Oct 15  2022 vst3sdk/vstgui4/vstgui/vstgui_standalone_mac.mm
27280644        8 -rw-r--r--    1 michaelgogins    staff                 239 Oct 15  2022 vst3sdk/vstgui4/vstgui/vstgui_uidescription_mac.mm
87797903        8 -rw-r--r--    1 michaelgogins    staff                1066 Dec  8 08:39 vst3sdk/vstgui4/vstgui/vstgui_mac.mm
michaelgogins@Michaels-MacBook-Pro ~/csound-vst3-opcodes % find vst3sdk -name "*_linux.*" -ls 2>/dev/null
87797251       24 -rw-r--r--    1 michaelgogins    staff               10470 Dec  8 08:39 vst3sdk/public.sdk/source/vst/hosting/module_linux.cpp
87797182        8 -rw-r--r--    1 michaelgogins    staff                2679 Dec  8 08:39 vst3sdk/public.sdk/source/common/systemclipboard_linux.cpp
87797186        8 -rw-r--r--    1 michaelgogins    staff                3078 Dec  8 08:39 vst3sdk/public.sdk/source/common/threadchecker_linux.cpp
87797467        8 -rw-r--r--    1 michaelgogins    staff                 921 Dec  8 08:39 vst3sdk/vstgui4/.github/workflows/cmake_linux.yml
87797902        8 -rw-r--r--    1 michaelgogins    staff                 627 Dec  8 08:39 vst3sdk/vstgui4/vstgui/vstgui_linux.cpp
27280278        8 -rw-r--r--    1 michaelgogins    staff                 607 Oct 15  2022 vst3sdk/vstgui4/vstgui/tests/unittest/lib/platform_helper_linux.cpp
michaelgogins@Michaels-MacBook-Pro ~/csound-vst3-opcodes % find vst3sdk -name "*_win32.*" -ls 2>/dev/null
87797253       40 -rw-r--r--    1 michaelgogins    staff               18714 Dec  8 08:39 vst3sdk/public.sdk/source/vst/hosting/module_win32.cpp
87797188        8 -rw-r--r--    1 michaelgogins    staff                3067 Dec  8 08:39 vst3sdk/public.sdk/source/common/threadchecker_win32.cpp
87797184       16 -rw-r--r--    1 michaelgogins    staff                5451 Dec  8 08:39 vst3sdk/public.sdk/source/common/systemclipboard_win32.cpp
27280645        8 -rw-r--r--    1 michaelgogins    staff                 274 Oct 15  2022 vst3sdk/vstgui4/vstgui/vstgui_uidescription_win32.cpp
27280280        8 -rw-r--r--    1 michaelgogins    staff                2380 Oct 15  2022 vst3sdk/vstgui4/vstgui/tests/unittest/lib/platform_helper_win32.cpp
87797479        8 -rw-r--r--    1 michaelgogins    staff                3989 Dec  8 08:39 vst3sdk/vstgui4/vstgui/contrib/datepicker_win32.cpp
87797482       16 -rw-r--r--    1 michaelgogins    staff                5345 Dec  8 08:39 vst3sdk/vstgui4/vstgui/contrib/evbutton_win32.cpp
87797905        8 -rw-r--r--    1 michaelgogins    staff                1319 Dec  8 08:39 vst3sdk/vstgui4/vstgui/vstgui_win32.cpp
27279820        8 -rw-r--r--    1 michaelgogins    staff                 717 Oct 15  2022 vst3sdk/vstgui4/vstgui/lib/platform/platform_win32.h
27280640        8 -rw-r--r--    1 michaelgogins    staff                 614 Oct 15  2022 vst3sdk/vstgui4/vstgui/vstgui_standalone_win32.cpp
michaelgogins@Michaels-MacBook-Pro ~/csound-vst3-opcodes % 

[gogins]

OK everything builds but the windows archive lacks the plugin DLL!

Maybe try PowerShell instead of 7zip?

https://stackoverflow.com/questions/1153126/how-to-create-a-zip-archive-with-powershell

[gogins]

It's vst3_opcodes.dll, not libvst3_opcodes.dll, that was the problem...