Bug fix/text input disabled

[oscar139]

In rearranging the calls to initialize ~MapViewState no longer leaves the status of SDL_TextInput off. This had the side effect of causing the NAS2D::Utility<StructureManager>::get().dropAllStructures(); in MapViewState::load where StructureManager was still populated with pointers from objects from the now deleted MapViewState.

Edit:
New strategy. I do not see any advantage of disabling SDL_TextInput by ~MapViewState.

[DanRStevens]

The second commit looks like the actual fix. The first commit I think may have some unintended consequences.

[DanRStevens]

I can accept this. Maybe slightly odd that we enable text input mode in two places, which can be called multiple times, and never disable it anywhere. But then given how we're using it, there's not really an obvious better solution. Particularly since text input mode is an on/off switch, without any kind of reference counting, and our calls to turn it on (and potentially off) are by classes that may have multiple instances, and those instances won't know about each other.

I'm wondering if it would make sense to enable text input mode globally somewhere early during app loading, and never touching it again.