Try to simplify tuple_cat. Mostly works
Make tuple_cat work with tuples of references. Demo app compiles & runs.
tuple_cat_jph.h -> tuple_cat.h
Split tuple_cat.h into tuple_cat.h & tuple_helpers.h
Introduce tuple_tail() & tuple_append()
Simplify the implementation of tuple_cat()
Add Bryan's second test
Merge pull request #1 from jaredhoberock/master

Simplify tuple_cat a bit