COMP: Fix all valid cppcheck warnings in ITK (last patch)

  Previously five patches were sent about fixing cppcheck warnings in
  ITK/Module directory.

  At the current patch, all other valid remained cppcheck warnings in
  the ITK directory are fixed. All the remained valid warnings were from
  Example/ directory.

  One example of invalid warnings are those that are about unused
  functions. This functions are not used in static analysis, but the are
  used by users in real applications.

  The fixed issues are generally about the following topics:

  1) In definition of class A:
    the 'A::operator=' should return 'A &'. However, they would return
    viod.

  2) Prefix ++/-- operators are preferred for non-primitive types.

  3) Initialization to assignment is preferred.

  4) If possible, variables are passed by reference.(This warning mostly
    happens about Exception catching).

  5) Emptiness of variables are checked efficiently using the empty()
  function.

  6) Unused variables are removed.

  All the ITK tests are passed after the above changes.

Change-Id: I00e4804b4e26dbc2e709d17a82279713be36f307
Merge topic 'NO_module_cppcheck'

a379365 COMP: Fix all valid cppcheck warnings in ITK (last patch)