Add static size checks

[DanRStevens]

Many structs and classes are designed to match the internal memory layout used in Outpost2.exe. As such, they are size and padding sensitive. We should add static_assert checks to ensure structs and classes have, at minimum, a size that matches what Outpost2.exe uses.

Particular attention should be paid to structs or classes that use varying size enums, such as map_id. Pull Request #17 touched on this.

A proposal for a helper macro is in Pull Request #18.

[Brett208]

Can we sign this off now, or are there more structs to consider?

-Brett

[DanRStevens]

A quick grep of the source shows there's still much more work to do. I'll probably try to complete this in sections.

Adding a space after "struct" helps filter some of the noise, and shows both struct definitions and the static size checks recently added. That gives a quick glance of what needs to be done. Should probably do this for classes too.

grep -rn "struct " *