stitch/placer: assertions against result files.
stitch/placer: assertions against result files.

Use the filefixture helpers already established in the transmat mixins.  (I started writing the same things again in the testutil package before catching myself, yikes.)  The dirtime fixing feature is necessary for correct fixture setup.

Signed-off-by: Eric Myhre <2346ad27d7568ba9896f1b7da6b5991251debdf2@exultant.us>

polydawn/rio,polydawn/rio