abspath and simple diff tests

I like tests.

Lacking a full fledged test infrastructure, simply diffing outputfiles is often sufficient.

Except for stuff like

a) using absolute paths related to where the source tree is

b) other time and position variant stuff.

I'd almost like a diff

1) that was smart enough to recognize and skip timestamps

2) that was smart enough to recognize absolurte/relative file patterns.


I have added relative/absolute file options to many tools - so often that I suspect it is not the tools fault, but really should be fixed in the test infrastructure.

I have preprocessed expected output files - but that can be fragile, if the preprocess tool breaks and, e.g., gives an empty string.