Added logging function to step probtrackx
	modified:   dwi_analysis.py
	modified:   tractography.py
Gradually adding logging functions to main and sub routines

	modified:   dwi_analysis.py
	modified:   tractography.py
Gradually incoporating logging into all subroutines

	modified:   aparc_utils.py
	modified:   dtiprep_utils.py
	modified:   dwi_analysis.py
	modified:   scan_for_dwi.py
	modified:   tractography.py
	modified:   tracula_utils.py
a	tract_seg.py