Fixes full-pathing links and being able to linkify links

[eric-hansen]

Resolves #39 and possibly #25

I don't think the regex considered WikiLinks (which is what I use) so this resolves that for the cases where [[SomeID.md|someText]] is trying to be linkified again. Not foolproof but at least is a start. Might be worth it honestly to wildcard before and after str.

[eric-hansen]

I'm not familiar with Markdown, but I did some testing in Lua REPL for the regex I have here:

 > lua
Lua 5.3.3  Copyright (C) 1994-2016 Lua.org, PUC-Rio
> line_wiki = "[[bz1l.md|test]]"
> line_wiki_ = "[[bz1l.md]]"
> line_wiki__ = "[[bz1l]]"
> line_md = "[bz1l.md](test)"
> line_md_ = "[bz1l](test)"
> print(line_wiki:match("%[bz1l.*%|?%]"))
[bz1l.md|test]]
> print(line_wiki_:match("%[bz1l.*%|?%]"))
[bz1l.md]]
> print(line_wiki__:match("%[bz1l.*%|?%]"))
[bz1l]]
> print(line_md:match("%[bz1l.*%|?%]"))
[bz1l.md]
> print(line_md_:match("%[bz1l.*%|?%]"))
[bz1l]

So far it seems to work fine.