DOC: Multiple Label LaTeX Warning

Label sec:BSplinesMultiGridImageRegistration was defined twice in
two sections with identical headings. Labels corrected, headings
corrected, example in DeformableRegistartion7.cxx corrected:
http://review.source.kitware.com/#/c/13813/.

Change-Id: I1ba2dc2242b36a8447f2abbb48ff1967dbb5cd11
Merge "DOC: Updates to Introduction/System Overview."
DOC: Updates to Introduction/System Overview.

Change-Id: I768337e5673fcf0afc94f81c68d89c5b8b152cdd
ENH: Set ITK tag to v4.5.0.

To align with the release.

Change-Id: I6f0d767b60ff49c7a370287f5b064007ae1c8ff3
Merge "ENH: Set ITK tag to v4.5.0."
Fix spelling of Lowekamp

Change-Id: I93511ffee81d21f5ef9cab4815ccd14c958f6a38