adding option set_as_scalar to parameters

This adds the additional member function to set the dim vec as a
scalar.

Change-Id: I0c12b4bc217b3c8b676983a9d0bd63bf20e7d8ac
document new set_as_scalar field

Change-Id: Iec769a7bbc611952904669b6ca624d9b64d6d8e6
Convert all public SetRadius methods to use set_as_scalar field.

Change-Id: I1571ce0cb14f1a8a0e530f53aa0d3d46ac1e7b68
Using set_as_scalar to add new methods to filters

Change-Id: I4b429d1e97c324ac8f567282bae63ba9ca648462
Adding set as scalar to image sources too

Change-Id: I9bf306515736d134c357c8ff12fbe91456e121be
Merge topic 'SIMPLEITK-440_AddScalarSetFordim_vec' into next

693c550 Adding set as scalar to image sources too
c16837f Using set_as_scalar to add new methods to filters
ebff82d Convert all public SetRadius methods to use set_as_scalar field.
9cf8d49 document new set_as_scalar field
3447475 adding option set_as_scalar to parameters