and: * add some flags * document them * move the customizable stuff to defaults.c

Initially I took the IRI parser from gmid, stripped of the UTF-8 things and transformed back into a URI parser. Then I've added some functions to resolve URIs, but it wasn't enough. gmid parser is aimed at servers, and so it doesn't handle very well relative links. This makes use of the libphos uri parser, which was coded to follow the RFC more strictly, and to fully support all kinds of URIs. It'll need to be expanded in the future and be improved for sure