Class for parsing and expanding URL
templates acording to the RFC6570 specification
(see https://tools.ietf.org/html/rfc6570). eg. template
= [GSURITemplate templateWithString:
@"/search{?q}"
relativeToURL: aURL error: &error];
Expands the template with the given
variables and reurns a new URL relative to
the given base URL or, if that is nil,
relative to the absolute part of the pattern with
which the template was created. In the absence
of any absolute part, this method returns a relative
URL.
Expands the receiver with the specified
variables, returning the relative part of
the result. Returns nil if the
template cannot be expanded with the
variables.