COMP: Review use of iostream & use double-conversion where needed
Merge pull request #187 from Chaircrusher/IOStreamDoubleConversion

COMP: Review use of iostream & use double-conversion where needed
COMP: Avoid continuous rebuild of ExternalPackages

New option added to that defaults to off for FORCE_EXTERNAL_BUILDS.
This needs to be turned ON to allow updating of external packages.

Needed to split the ExternalProject command and argument into separate
varables for their effect to work.  Otherwise they were having no
noticiable effect on the build system.
BUG: Compile errors w/packages turned off by default.
Merge pull request #188 from Chaircrusher/DoubleConversionFixes

BUG: Compile errors w/packages turned off by default.
BUG: check wrong var when writing out gradient vectors
Merge pull request #189 from Chaircrusher/GTractResampleInPlaceBug

BUG: check wrong var when writing out gradient vectors
BUG: Fixed faulty thresholds for WM partial volumes
fixup! BUG: Fixed faulty thresholds for WM partial volumes

Conflicts:

	AutoWorkup/brains/metrics/partials.py