Proposal to split up plugins API into its own module(s).

[Matt Sicker <bo...@gmail.com>]

In order to support LOG4J-595, technically, I think it could all be done as
part of the core package and would still work. As a matter of design,
however, I'd like to propose the following split:

log4j-core-api:
 - Contains the main interfaces used in the core module but not specified
by the api module
 - Would also contain the annotations
 - Optionally, we could also include some abstract classes here, too

log4j-core:
 - Contains the rest of log4j-core that wasn't removed (some classes may
need to be updated or moved around to avoid splitting packages across more
than one module).

log4j-plugin-processor:
 - Contains the PluginManager along with the annotation processor code.

Going this route would allow 3rd party plugin writers to depend on less
code in order to implement their own plugins. It would also help our own
code by allowing more fine-grained modules if we want to go that route
eventually.

Like I said, though, this isn't entirely necessary. I just like the idea,
but I would need buy-in from the rest of us to go forward with this idea.
I'm not sure which type of vote would be appropriate here, but I'd imagine
it would be one of the member-or-higher level votes.

-- 
Matt Sicker <bo...@gmail.com>