expand tests to cover all the typed rule cases now that its fully generic

[heckj]

Rules were previously existential, and writing closures that used the modules required casting. With update #21, that's notable changed - all the modules are shifted into fully typed expressions, and the rules are all generic across a couple different Axis, resulting in a combinatorial explosion of types:

Context matching:

• direct
• left, direct
• direct, right
• left, direct, right

matrixed against:

• basicLSystem (no parameters, no RNG)
• RNGLSystem (no parameters, RNG)
• DefinesLSystem (parameters, no RNG)
• DefinesRNGLSystem (parameters and RNG)

Some of the code is verified, but it should all be basically "worked" to verify that I didn't miss anything while making "the maze of twisty passages, all alike" in order to have typed closures for writing LSystems.

(Coverage of Lindenmayer in general dropped to 36%)