Updates tests to be mostly TAP compliant. Adds a few tests. One Array fix.

This PR adds a few fixes and repairs tests to run through tinytap, needed for the runtime-qemu rig (and general correctness).

* Updates all non-tap-compliant runtime tests to be TAP compliant, anticipating a switch to tinytap for runtime tests (as it is in runtime-qemu rig)
* Adds / refactors a few tests.
* Fixes an Array splice bug on master.
I see. That information should be included in the actual test file, because it's really unclear what is actually being tested. I wonder if there is a way to mechanically copy the contents of those bug reports into the test files as comment blocks...?