how to download and install externals

[Richard K. Herz]

At http://reactorlab.net/intro/externals.html
are brief instructions for downloading externals from a server and using 
them on a client in a Rev application. The instructions are trivial for 
Windows but nontrivial for Mac OS X. In my application, I wanted a client 
Rev app without the revxml external to be able to download and use stacks 
which require the revxml external. The instructions should apply to other 
externals.

Rich Herz