rect: Addition.
rect: Subtraction.
rect: Multiplication.
rect: Division.
vector: Divde-by-zero test now uses comparison fixture instead of binary func.
test: Comparison fixture contents are now const.
test: Binary func fixture contents are now const.

- Also renamed m_result to mcb_expected_result.
rect: Negation.
rect: Simplified quite a few tests.

Rect isn't testing vector contents, just that it works over vectors.
When possible, we use canned vectors from a preexisting table. This
way, instead of varying each vector param independently, making the
set of all combinations for a given test quadratic, we vary an index
into the canned vector table, making them linear.

In most cases, we just test once, composing over the encapsulated
vectors. Some cases, however, like division by zero, must be drilled
down a bit.