New ParseSpec() and FormatSpec() methods allow you to convert
specs between hash and string representations easily. Shortcut
methods Parse* and Format* are also defined. (i.e. FormatClient()
and ParseLabel() etc.)
New methods IsTagged() and IsParseForms() tell you if your client
is in tagged/form parsing mode respectively. If you care.
P4::Tag() is deprecated in favour of P4::Tagged(). P4::Tag() exists
for backwards compatibility