Silenced compiler warnings

[PatrikLundell]

Summary

None

Purpose of change

Silence a bunch of compiler warnings (with the rather futile hope to one day reach a state where the appearance of a warning means it's something you've just caused, and thus needs to deal with).

Describe the solution

• Silenced a template type conversion complaint fouling the compile log with a bunch of references every compilation by turning an implicit conversion into an explicit on.
• Changed obviously incorrect && into || (being different from at least one of two flags will always be true). Cannot guarantee the change is the correct one, but looks reasonable.
• Changed bitwise comparisons into the boolean ones they probably were meant to be.
• Changed a whole lot of loop variables into const & ones (const sometimes present already) after checking if they seems to actually be assigned (found none in my checks).

Describe alternatives you've considered

Also trying to silence many of the complaints about switch fallthroughs. It appears C++17 has the [[fallthrough]]; directive the compiler can interpret (rather than the various human produced comments present in a lot of cases).
Haven't tried to do it as I'm not completely certain that will work for all compilers used by the project.

Testing

Loaded save, walked up ramp, jumped into car, ran through hay bales, ran over a turkey, smashed into a stationary vehicle. Didn't see anything odd.

Additional context

There are a lot of warnings about:

• Access via null pointers (some reasoning being incorrect, such as assuming casting of a Creature into an npc resulting in a nullptr must mean casting into a monster also has to result in a nullptr). Many may be relevant, though.
• Stack footprint of operations being excessive.
• Use of a moved from object.
• Stuff in imgui and flatbuffer, but I assume they're "as is" and shouldn't be touched, as they're marked as third party.
• Some odd bits and ends, some of which seems to be the compiler making assumptions it cannot logically make with the information available.