Implements nearly all of the test logging methods for both T and B
structs. Majority of the code has been copied from:
golang.org/src/testing/testing.go
then updated to match the existing testing.go structure.
Code structure/function/method order mimics upstream.
Both FailNow() and SkipNow() cannot be completely implemented,
because they require an early exit from the goroutine. Instead,
they call Error() to report the limitation.
This incomplete implementation allows more detailed test logging and
increases compatiblity with upstream.
