adium: allow build without building Adium
Working on feature #101 revealed that only the compiled frameworks from
an Adium build are actually required to build the plugin code. Building
the plugin by itself is considerably faster. The only drawback is that
you can't debug the plugin.
- add a script to the plugin build that detects a combined (the default)
or a separate Adium build.
- the script creates a directory with symbolic links to the compiled
frameworks from a separate Adium build.
- add the generated directory to the framework search path.
- update the documentation to describe the alternative build approach.