Add option to enforce template uniqueness

[arthens]

What this is

Add an option (disabled by default) to check that all the routes are unique

[arthens]

@rbone thoughts?

[lox]

Wouldn't you often actually want to override routes? Especially if you start adding routemaps to bundles?

[arthens]

Personally I prefer a stricter approach. Particularly with bundles, because if we decide to have bundle-specific route files (like symfony does) then you can't rely on ordering.

What is the advantage of overriding instead of replacing?

Like right now we have a couple of duplicates, and in all cases the overridden routes are completely unused and should have been removed.