Added various utility functions for manipulating pathnames

Since the test package uses :unit-test, which may not be loaded when
the cl-fad system is loaded, we can't define this package in
packages.lisp

Reordered documentation sections so that functions are grouped by what they do (instead of a semi alphabetical listing)

Added various utility functions for manipulating pathnames and the path package with shorter function names.

git-svn-id: svn://bknr.net/svn/trunk/thirdparty/cl-fad@4668 4281704c-cde7-0310-8518-8e2dc76b1ff0

git-svn-id: svn://bknr.net/svn/trunk/thirdparty/cl-fad@4667 4281704c-cde7-0310-8518-8e2dc76b1ff0

git-svn-id: svn://bknr.net/svn/trunk/thirdparty/cl-fad@4624 4281704c-cde7-0310-8518-8e2dc76b1ff0

git-svn-id: svn://bknr.net/svn/trunk/thirdparty/cl-fad@4455 4281704c-cde7-0310-8518-8e2dc76b1ff0

git-svn-id: svn://bknr.net/svn/trunk/thirdparty/cl-fad@4378 4281704c-cde7-0310-8518-8e2dc76b1ff0