Added functionality

To CreateROI.m:

1. Solved rare issue where the B1+ map of a single channel has a voxel or voxels that are zero in a position where the other channels do not. This causes an error when reshaping the masked B1+ maps to nVox by nCoils. The patch masks all channels by a mask which is set to zero if any channel produces zero field at that pixel.

To B1Shim.m:

1. Added additional function output (optimized TxScaleFactors)
2. Scale the optimized TxScaleFactors to create the same 80th percentile of B1+ as TrueForm, then scale to have the reference voltage produce the 90th percentile. This isn't all-encompassing and doesn't match the scanner, but it gets you in the right ballpark if you want to do a quick test on the scanner.
3. Phase printed to screen is relative to the first channel.
4. Added 80th percentile of the SAR efficiency to the output specs
5. Added two more cost functions

Validated changes with unit tests.