Remove documentation feature/Penlight/Fennel

These were some experimental features I was testing out really early in development to see if they would provide any benefit. As for why they didn't:

Documentation was constantly indexed at startup, which ate up a lot of time, and it was complicated to maintain. It wasn't worth the maintenance burden as opposed to autogenerating a website, and most people would prefer to use a website instead of some obscure feature for hardcore programmers.
Penlight was required by ldoc, which was used for the documentation system. It was not used for any other purpose, although a few libraries from penlight live on inside extlibs.
When I was trying to determine what language would work best for OpenNefia, I was originally thinking of a Lisp of some kind, given that Lisps are known for their extensibility. I remember trying Common Lisp at one point, but the only real support it had for game engines was a low-level binding to SDL, which wasn't simple to use at all. Fennel was just a way to live out that parenthetical fantasy in different manner. However, it turns out that needing to maintain mods in more than one language with radically different syntaxes increases the burden on developers. Keeping everything in one language means that people that look around in the source code won't have to learn a new language just to understand what's going on. (I think this was one of the main reasons Emacs was so successful, being that every extension for it is written in Emacs Lisp, and it was why the Xi editor's support for using any arbitrary language to write extensions was disappointing to me.)

Ruin0x11 / OpenNefia