use proper token definition in regexes

[clux]

In many places we use (\w*) or less commonly (.*) as a shorthand for what rfc4566's definition of a token:

   token-char =          %x21 / %x23-27 / %x2A-2B / %x2D-2E / %x30-39
                         / %x41-5A / %x5E-7E

   token =               1*(token-char)

worth going through and making this conform to the standard where it references token as it would make the library more resilient against future updates to various identifiers undoubtedly introduced in the future.

First seen in #53 ( pr #54 )

[clux]

think i found another one:

a=rtpmap:107 vnd.onvif.metadata/90000

parses as invalid in the coverage.test