Fix import path for the main macaco pkg
Add sprint and sprintln in macaco.fmt
Don't set the Content-Type header when it's been already set
Allow - in the middle of a program name
Set _parses_doctype_node in macaco.html to true

Allows telling apart when the implementation parses that node type
Allow exported structs to get a pointer to the original variable

This allows those types to call any methods defined in JS.