Having stated the principle in the previous commit, I should apply it
consistently. A source file linked into the Puzzles library of common
support code should not also define a main() under ifdef.
This commit only goes as far as the _library_ support modules. It
would be a much bigger job to do the same for all the actual _puzzles_
that have test main()s or standalone-solver main()s. And it's not
necessary, because modifying one of those source files only triggers a
rebuild of _one_ puzzle, not absolutely everything. (Not to mention
that it's quite likely the puzzle and the test main() will need to be
modified in conjunction anyway.)
As in the previous commit, this has required exposing a few internal
API functions as global, and maybe editing them a bit. In particular,
the one-shot internal function that divvy_rectangle() loops on until
it succeeds is now exposed as divvy_rectangle_attempt(), which means
the test program doesn't have to condition a failure counter into the
real function.
I've thrown away penrose-vector-test completely, because that didn't
look like a test program with any ongoing use at all - it was surely
vestigial, while James was getting the vector representation up and
running in the first place.
I noticed while hacking on hat-test recently that it's quite awkward
to be compiling a test main() program that lives in a source file also
built into the Puzzles support library, because every modification to
main() also triggers a rebuild of the library, and thence of all the
actual puzzles. So it's better if such a test main() has its own
source file.
In order to make hat-test work standalone, I've had to move a lot of
hat.c's internal declarations out into a second header file. This also
means making a bunch of internal functions global, which means they're
also in the namespace of programs other than hat-test, which means in
turn that they should have names with less implicit context.
