We use the Atlassian ''Bamboo'' system to automatically build
the project, run the test, and present the results, but the
system is not an oracle: it requires test results to be in
one of the several forms for which it has parsers.

I was able to construct XML files that Bamboo's "JUnit Results"
parser was able to handle. This commit introduces a simple
implementation of a file writer for those files.

This is a ''bare-bones'' implementation, onto which we can
hang future enhancements. Note that there are rules for
quoting data in strings, and text not within <..> tags;
the simple approach taken here is merely to completely avoid
the use of any character that needs quoting.

My intention is to continue work on this when I get back
from vacation on the 23rd.