Route state field should be just T

[hgzimmerman]

Description

Route has a state field that is currently Option<T>.
The reason that this is an option is because stdweb's API doesn't support getting the state outside of an event.
This can still be shimmed in using the js! macro.

[hgzimmerman]

This issue in stdweb is related: koute/stdweb#371
If anyone sees this, I would be willing to port my implementation to stdweb after it is done here.

[hgzimmerman]

Given the description of the api here: https://developer.mozilla.org/en-US/docs/Web/API/History/state

It appears that either the Option must stay, or the type T must implement Default, because the value returned by history.state may be null.

Since Default is already a bound on T, I'm inclined to go forward with removing the option