[PATCH] purge: add the clean alias inspired by git-clean and svn-clean

[Rafael Villar Burke]

Emanuele Aina wrote:
> I was used to cvs-purge from cvstools, so the extension was called purge.
>
> Recently I noticed that other SCM have the same functionality under the 
> 'clean' name, like git-clean, svn-clean (from the subversion-tools 
> package), and bzr clean-tree (from bzrtools), so I thought that some new 
> user could find the alias useful, given that the change is minimal.
>   
Besides the very standard 'make clean', to achieve the same results.
+1 from me for the clean alias

Rafael Villar Burke