Make ReflexiblePremaniplex function

[CunningGabe]

Right now, ReflexibleManiplex sometimes builds things that are pre-maniplexes only, if you hand it a group with some r_i trivial etc. We should instead have ReflexiblePremaniplex, and then have ReflexibleManiplex kick you over to ReflexiblePremaniplex if necessary.

[CunningGabe]

There now is a ReflexiblePremaniplex function 5f23f4d1c8596c990fd81f99ddc7178b4a6bf2b4.

I talked with Mark some about this, after realizing that it is not really feasible to check whether every generator is nontrivial and distinct. (i.e. we run into Word Problem issues). I added a warning to the documentation that if you call ReflexibleManiplex with some groups, you might get back a pre-maniplex masquerading as a maniplex. At the moment, I think that's mostly harmless -- most functions should work the same way on both maniplexes and premaniplexes. But if I run into something where that distinction is especially important, I may rethink this position.

So for now, I'm closing this.