Fixed the weird behaviour problem by defining types for each of the ast
nodes and then referencing those types when defining the ast type.

Unclear why this works, but I imagine it has to do with the types not
being a big part of the compilation process or something.

This also uses the typed_struct library to do so. Seems pretty slick and
does what it claims it does.

This basically just adds svg elements as void and nonvoid element
aliases and it works, will test on a real proejct before releasing the
next release.

This complicates the code, and since they are already deprecated, those
who are writing Temple probably won't be using them