Remove the other attribute matchers.

[hgzimmerman]

Description

Because you can't have arbitrary syntax tokens within an attribute, you either have to use #[attr(arbitrary stuff)] or #[arbitrary] #[stuff]. I find these to be difficult to read, and harder to write than just having a block of them, or just using the routing syntax exposed by #[to=""].

Because the router syntax is a little more manageable now, it might make sense to get rid of all, or at least some of the attributes. I don't think there is a need for two separate systems.
Keeping #[rest] and #[end] are probably worthwhile, but everything else except #[to=""] should go.

[hgzimmerman]

This issue would remove the need for #98