Improvements to util.touch() and tests
 - Find the right script in test_align.py
 - Better control of test conditions in test_fx.py
 - Make touch() update both atime and mtime in util.py
Add tests for functions in util.py. Also,
 - Remove duplicate expand() from fx.py in favor of the one in util.py
 - util.contents() should strip newlines from input
 - util.abspath() now accepts and can compute from a start path other
   than cwd