Fixed small bug in the design creation.

Even when no numbers are to be presented trials were created with
numbers in them, but not actually presented. The problem is that this
placed a restriction on the model selection.

It also seems that with the current list of eligible letters that no
more then 7 letters max can be displayed.
moved the fill in design code from the WIP to the final folder
Added the ability to present up to 8 letters. Now just need to update the GUI with this ability.
added a PILOT version of the task that includes higher number of letter presentations and modified the number of trial calculation to be more generic. This also allows modification of the letter set sizes from initialization scripts.
Finallizing the PILOT version of the task with up to 7 letters.

With the current set of usable letters at most 7 letter presentation
set sizes can be used.
The extra load levels works and the program has been tested. The problem is that the current available letters does not allow paradigms with more then 28 trials for sets of 7 letters. And no trials for sets of 8 letters.
The additional letter loads work weell and the design efficiency has been improved. The last step is to finalize the design and create optimal ITI distributions.
Optimized design creation and finished presentation of 1 thru 8 letters.

Finalized 8 letter presentation using 15 letter pool. I tried with 14
letters but only sequences of 16 trials were possible. So I added the
letter P back to the pile and it can work now. I also had to modify how
designs are created based on the letters used for that trial and the
ones NOT used for the prevous trials. This allowed easier design matrix
selection and creation. Optimization of the design showed that a 3 3 3
design duration was much more efficient then a 3 2 3 design duration.
Now I need to fix an error in the instruction presentation.
merged devlop into master