Python3Enabled (python executable + import lib + cffi)
PerlEnabled (perl executable + perl runtime DLL + gendef.exe)
InstallerEnabled (Inno Setup iscc.exe).
Updated the Python plugin project to compile only when Python3Enabled is true, and otherwise emit a clear skip message instead of failing prebuild/import steps.
Updated the Perl plugin project similarly to gate build steps on PerlEnabled and print a skip message when prerequisites are missing.
Updated the installer project so it only uses C++ targets when InstallerEnabled is true, with a fallback skip message when Inno Setup is unavailable.
- Output directly to rel\ instead of to bin\ and then copying files over.
- Deduped Win32 vs x64 configs
- Moved some common properties to hexchat.props
- All build intermediates (except htm's intermediates) are no longer emitted in the source directory
