BUG: QCXML overwritten during visual check

[rgsmith3]

When doing visual checking and saving VC files, DTIPrep1.2.4 by default writes new files with "VC" in the name. The exception is the QCXML file. That one is overwritten, instead of writing a new file, and it does not appear to retain the original processing information. Please change such that when saving VC files, a new QC XML file is output. Thanks!