Allow user macros to target specific spaces

It would be great if user macros could be defined to target specific spaces, instead of being accessible across an entire Confluence instance. A couple of advantages of this improvement are:

• Reduces clutter in the macro browser
• Prevents space-specific macros from needing to have names like [SpaceName][MacroName]
• Allows macros with similar, although slightly different, functionality to share the same name

This improvement request is somewhat similar to CONF-7826, but does not focus on who can create space-specific macros.