Garbage param/preset/... names when maximum string size reached

[helgoboss]

This is caused by a bug in the copy_string function that can cause a missing nul terminator:

vst-rs/src/interfaces.rs

Line 76 in ab74a56

memcpy(dst, src.as_ptr() as *const c_void, min(max, src.as_bytes().len()));

It should be max - 1, otherwise the nul terminator set by the previous statement will be overwritten and the C string becomes open-ended ... undefined behavior when the DAW reads this!

I'm aware that usage of this project is deprecated but I think there are still some plug-ins out there using it, so hope this helps.