Random parameter tweak attempts

Decrease num context features from 25 to 20, increase WM decay, increase
context resample to double.  Will try longer number of presentations per
trial so that there can be more competition based on matching context.
Decreasing WM decay

Previous run attempt caused WM decay to dip below 0.5 meaning lures
ended up with higher WM memory strengths than targets.  Decrease WM
decay to 0.248