Honor changing view controller type.

[hkfb]

Background

When replacing existing Views with changed Controller types, if the new Views happen to have the same ids, then the new Controller types are not honored, and instead the old, possibly incompatible Controllers are used instead.

Change List

• Create new Controller if type has changed

[felixpalmer]

This doesn't check if the view has changed, as the original TODO mentions. Could you also add that? Please also add some tests that demonstrate that this works

[hkfb]

This doesn't check if the view has changed, as the original TODO mentions. Could you also add that? Please also add some tests that demonstrate that this works

I think it's the view / controller combination that is the intention of the TODO comment. The change of the View is handled elsewhere.

I added a test that demonstrates the issue. It fails without the changes in this PR.

[hkfb]

@felixpalmer would you mind taking another look?

[coveralls]

Coverage: 89.831% (+0.0005%) from 89.83% when pulling 3237e90 on hkfb:invalidate_controller into 96ce058 on visgl:master.