Stop translating BOOL to bool

[AArnott]

Fixes #362

[sylveon]

I'd personally not add the implicit conversion operator, as it encourages the while (GetMessage(...)) kind of code, which is explicitly pointed out as wrong in the docs for GetMessage. Or maybe this special case is something an analyzer could handle.

[jnm2]

That would hurt usability of all APIs that use BOOL for the sake of one or two that are this way, right?

[sylveon]

That's why I suggested adding an analyzer instead, that would warn for such usages.

[AArnott]

I imagine analyzers could be a huge win for users. But also a bottomless pit of work. If folks are interested in sending PRs that add analyzers, I will try to find time to add the first one as a template for how more can be added.