Clearer names for saving and running

Initially I referred to many things via EM such as EM_trial_simulation,
but this stopped making sense when we also incorporated the WM side.
Also, I had hardcoded the place to save (or load) simulation results
which doesn't generalize to other people running my script cause they
would have to change this value in many places.  Lastly, most of my
simulation result variables were called this.

Add central save location in PM_task via PM_task.SAVE_DIRECTORY
property.  Modify save and loading simulation functions to use more
appropriate variable names as well as new PM_task.SAVE_DIRECTORY
property.
Create README.md

Version 1 of the readme - will likely need to revise this.
Turn script into function (better style)

Previously the function plotLureVsTargetStrengthsAcrossTrials was a
script which assumed the existence of some variable 'this' with the
correct type.

Modify script to be function, duh.
Update README.md
Log Right Item, Wrong Context Rehearsal Failures

To further diagnose how the EM noise and WM decay interact, it's
necessary to dissociate WM rehearsal failures that retrieve different
instances of the current target item (right item, wrong context) against
the more detrimental wrong-item, whatever-context failures.

Return extra value in REMplusWM.m updateWMifNeeded and log it in
Trial_Simulator.m
Change default model parameters

This is being done to investigate differences in WM reliability between
the cases of high PI, no EM encoding noise and yes EM encoding noise.
To do this, must standardize parameters being used across both cases.

Modify the values in REMplusWM.m and also
runSimYesDecayYesRehearseYesEMnoise (although this change is looking
forward)