Prior to implementing canvas suppor they were in the order they are in
the scenes dock.
After switching from obs_frontend_get_scene_names() to
obs_canvas_enum_scenes() this seems to not always be the case.
The "core" macro conditions and actions have been extracted out to the
"base" plugin.
The library now mostly contains functionality which is required across
all plugins and (e.g. definitions for macro segments).
The goal is to reduce the complexity and cross-dependencies and group
the source files in a better way.
This should relsove the "library limit of 65535 objects exceeded" build
issue occuring in some Windows build environments.
