[lmi] wx_test cleanup

[Greg Chicares]

I anticipate running 'wx_test' frequently--perhaps before every
commit--which makes the following side effects inconvenient; can
they be suppressed?

(1) It creates at least eighteen files in /opt/lmi/bin where I
run it. That's how the program normally behaves, so that's how
the tests should work: it'd probably be a bad idea to test in
a different directory. Therefore, wouldn't it be best to delete
them when the test is finished?

(2) Apparently 'configurable_settings.xml' is modified. Would
it make sense for 'wx_test' to rename it at the start, then
rename it back at the end?

(3) File history also changes. Is there any way to save the
original values before the test, and restore them afterward?