ENH: Make using 64-bit int pixels optional

The Visual Studio 2008 linker is running out of memory with 64-bit
integer pixels so add a user option to turn it on and off and default
it to off just for VS9.

Change-Id: I855421c90b2f5d981488522b1f3a459042efb0ff
ENH: update tests to optionally check 64-bit integer pixels

Change-Id: I07c35ad7fe0e262dadaafc6d8a62b11cde516862
Merge topic 'SIMPLEITK-397_AddInt64Pixels' into next

21ba4d4 ENH: update tests to optionally check 64-bit integer pixels
c9e9056 ENH: Make using 64-bit int pixels optional