This adds test.check tests for `vector/_last`. This is _really_ similar to `vector/_first` (and the other vector tests), so I think there are definitely ways to extract common logic from these.
The original version just used the built-in `first`, which returns `nil` if you give it an empty collection, which is almost certainly not a useful behavior.
This changes it to return `:ignore-instruction` if the vector is empty, thereby leaving all the stacks unchanged.
`make-instruction` will ignore any instructions that return `:ignore-instruction`. This allows instructions to be skipped without consuming their arguments.
There were two independent bugs in `vector/_subvec` that were turned up by our `test.check` testing.
The first was that the order of the arguments was wrong and `stop-raw` and `start-raw` were flipped.
The second was that `stop` wasn't max'ed with 0, which meant it could sometimes be negative, leading to an `IndexOutOfBoundsException`.
This is a start on using `test.check` to write tests for the vector instructions. We currently have tests for:
* `vector/_emptyvector`
* `vector/_indexof`
* `vector/_subvec`
There are _lots_ of other functions still to be tested.
This did reveal errors in `vector/_subvec`, which will be addressed in the next commit.
We used macros to make it easy to generate tests for each of the four vector types; this should be extensible to additional vector types in the future if needed.
This change uses the first command-line argument as the problem, which is assumed to be a namespace under `propeller.problems`. This will load the `instructions` and `error-function` from that namespace. If no problem is specified, then a (hopefully) helpful error is generated and the programs exits.
This allows us to call Propeller with calls such as:
```
lein run software.smallest
```
This creates a `push/utils/globals/cljc` similar to that created by @mcgirjau and moved the `max-stack-items` def to that namespace, updating `polymorphic` as necessary.
