Version 3.1.1 finally removes the "magical" pre-pend of checkout to relative paths in the environment and 
some config file values. Instead, it exports the environment variable TEXTTEST_CHECKOUT so you can
be explicit about when you want this.

For example, where before you might have said in the config file

binary:source/myprogram

assuming this would be interpreted relative to the checkout, you now need to say

binary:${TEXTTEST_CHECKOUT}/source/myprogram

