TempStackCString : Refactored class so core array can be used for more cases.

Class used to be hardcoded to 255 Utf8Char elements + 1 for 0 termination. Now a template is used
internally so other fixed arrays can use this design patter as well.  This is a staging to allow a fixed sized
initial array that can spill to dynamic allocation if necessary. At that point, perhaps even the fixed size
initial buffer is not that helpful. Either way, trying to move more code to the common API pattern.
TemplateTypes, SubVector: Working to support multiple template parameters

Name change: SimpleSubVector changed to SubVector.
The FixedCArray now derives from SubVector. This adds one pointer to the structure (_begin)
and means FixedCArray derivatives can be directly passed to functions that take
SubVector* arguments.  Consolidated some argument limit checking.
More to do.
UnitTest: TooManyArguments.via updated (limit is 100 now , not 32)