srfi-66 and r6rs-libraries eggs

Hello!

two new eggs are available:

srfi-66 (adds a few procedures to what's provided in srfi-4)

r6rs-libraries (SRFI-83 compliant port of Andre van Tonder's
  "simple-macros" with automatic `require' and better integration
  into chicken - this is really quite interesting!)

Note that the r6rs-libraries egg needs some linker stuff in it's
setup script (the wrapper-libraries for standard chicken units are
put into a library). I have only tested this on linux and the exact
linker invocations for MacOS and Windows might be wrong.

Anyway, feedback is welcome.


cheers,
felix