BUG: move SWIG template instantiations to before other filters

Filters like the CastImageFilter were missing the ProcessObject base methods.

Remove redundant explicit wrapped headers in interface specification,
and re-ordered into more logical groups.

Change-Id: I710c2de6f66ac82ebbee442fed39734c2ce05ab4
BUG: Add dependency for SWIG on all header files in Code directory

Change-Id: Ibd112366380da9d0bded46b030ba5ac1a05f14b0
ENH: Adding global warning option to ProcessObject base class

Change-Id: I207f86700edf5dd1de414cf706a57ff7491964c2
Adding basic test for ProcessObject GlobalWarningDisplay methods

Change-Id: I6a65218d35de62db04a0fbbefe9c2614b97ad618
ENH: Adding process object command callbacks

Adding generic Command class which has execute method to be called on
callbacks.

Added referencing between ProcessObject and Command to allow automatic
decoupling for stack based construction and cleanup.

Adding Event's as enums.

Adding override-able infrastructure in ProcessObject to allow for
derived classes to customize behavior.

Adding Progress as an active measurement, to be accessed during
command call-backs.

Change-Id: I44c8213f005308c10b09579286c5128657f9c4d2
ENH: Adding C++ example to report progress

It's a test too

Change-Id: I2ce44e22438af1c7eba4e2bf1a9abdc9ef842dce
Merge topic 'SIMPLEITK-453_AddEventCallbacks' into next

3af446e6 ENH: Adding C++ example to report progress
691e688c ENH: Adding process object command callbacks
85ecb039 Adding basic test for ProcessObject GlobalWarningDisplay methods
0aa39f9e ENH: Adding global warning option to ProcessObject base class
b80a101c BUG: Add dependency for SWIG on all header files in Code directory
dead7f18 BUG: move SWIG template instantiations to before other filters