[libiri] "@" parsing within autority when it's valid hierarchical part character

[libiri] "@" parsing within autority when it's valid hierarchical part character

[Issue#] LINUXWRT-338
[Problem] parseIRI bug
[Cause] Before "@" wasn't skipped in any case and treated as autority part always
[Solution] Add code for checking if "@" is in autority part of ti's hierarchical part character
[Verification] Build repo, use test binary from tests/.libs/iridump. IRI: should have host part correctly set.
IRI: http://mt1.googleapis.com/vt?lyrs=m@216094057&src=apiv3&hl=en&x=28717&s=&y=13011&z=15&s=Ga&scale=2&style=59,37%7Csmartmaps should have host part correctly set.

Change-Id: I0c5b5a4e4c7be1fe2e153fd3d0087b13cdc0d11e