Moved adding targets from constructor to produce method.
Removed second condition as it is implied by the third.
Pretend feature is complete now, if utterly untested.
improved ducumentation of -u feature
bugfix: don't mark a target as out of date just because it depends on an out-of-date depend target
New test abstraction: modify some files, run a function (typically produce with a certain set of arguments), then check which files were modified.
Unit test for new pretend feature, not tested yet.
increased caution: now sleeping a sec before touching files at the beginning
test for pretend feature works now