COMP: Fix all valid cppcheck warnings in "Module/Registration" directory

The cppcheck is run inside the ITK/Module/Core directory and all the
valid cppcheck issues are fixed.

Some of the cppcheck warnings are related to the functions that are not
used, but they may be used later by users. Such a warning is an example of
invalid warnings.

The titles of major fixed issues are listed below:

- prefix ++/-- operators are preferred for non-primitive types.
- initialization to assignment is preferred.
- if possible, the scope of variables are reduced.
- initialization of variable in initialization list is preferred than
assigning variable in constructor body.

All the ITK tests are passed after the above changes.

Change-Id: If152f4b061f5e99ef39af9aa2685f63de5630344
Merge topic 'registration_cppcheck_perf'

76d7f46 COMP: Fix all valid cppcheck warnings in "Module/Registration" directory