iri: copy portstr too

iri: make mergepath take a buffer and strings, not the iri pointers

iri: change remove_dot_segmens to take a buffer instead of an iri

iri: zero iri_flags before parsing

iri: use a temp buffer for %enc in iri_setquery

add some tests for iri_setquery

tests: tweak logging on iritest

iri: implement iri_setquery

s/check/resolve

fix add_proxy path check IH_PATH is almost always defined, check that the path is the empty string.

iri: fix port parsing

iri: support framents and enable fragments tests

iri: add tests for the parser

iri: rewrite remove_dot_segments to be clearer the previous version was straight out RFC3986 (more or less, it had a bug I didn't spot), but it's ugly and extremely long. Rewrite it to be somewhat inspired by canonpath (from kern_pledge.c) and way simpler. There are some small differences in how UNIX paths and URLs paths are canonized (in UNIX path you don't care too much of a trailing '/', in URLs you do.) The new code is more clear and passes all the tests in RFC3986, so I'm calling it a win.

iri: fix remove_dot_segments algorithm i've misread the description in the RFC; we should copy up to, but not including, the next '/' at the end and manually inject some '/' in some other cases.