Avoid error when there are no cctbx extension modules.
Respect the SCONS and EASY_INSTALL parameters.
Use source archive for PyCifRW.
Insert relative paths to cctbx.pth.

Added section for converting absolute paths in cctbx.pth.
Fix fetch functions to preserve working directory.
Do not use readlink, does not work on Mac.
Add function for fetching from mercurial repositories.
Build pycifrw from mercurial repository.
remove make in pycifrw building and add change options for change director of src fetching
add 03-package.zsh
create directory before copy file