Shen/tk upgrade in Lib

[dr.mt...@gmail.com]

I've fixed a bug in Shen/tk involving relative and absolute pathnames which was triggered by the use of cd in shen.  The bug was in Shen Lib.  The new Lib, along with executables for Shen/tk under SBCL and Scheme (Windows only) is also available on the download page.

Mark