srfi-tools egg

[Lassi Kortela]

We now have an up-to-date .egg file for the `srfi` command line tool, a 
new program maintained by the SRFI Editor and volunteers to help run the 
SRFI process.

The source tree is here: 
https://github.com/scheme-requests-for-implementation/srfi-common/tree/master/srfi-tools

Typing `chicken-install` in that directory builds a working `srfi` 
executable. (We should have ironed out most of the bugs by now, but a 
few doubtless remain.)

Would it make sense to add this egg to the Chicken coop? We can write 
the requisite wiki page for it.