Debian/Ubuntu package for RLisp

Easy installability is very important - wasting 5 minutes for a few thousand of users means a few weeks of lost productivity - and everybody wants thousands of users, right ?

So RLisp now has a Debian/Ubuntu (.deb) package, and a man page. Man page was generated with docbook. I'm not sure if I like Docbook or not, It feels way overmarkuped compared to Perl POD and its derivatives which I usually used for manpage generation.

Among the minor things that changed is environmental variable RLISP_PATH, by default /usr/bin/rlisp:/usr/local/bin/rlisp, which now controls where RLisp looks for libraries requested by (require "lib.rl"). Maybe I'll change it to use Ruby search path if I ever integrate (ruby-require "arubylib") with (require "arlisplib.rl").

A .deb package also means RLisp needs a versioning scheme. For now all versions are 0.1.YYYYMMDD, where YYYYMMDD is checkout's date.