Moved the code page 437 mapping table to winnt.c so that it could be
used in window and console clients.
Added check that fonts support unicode values we use from code page 437.
Use unicode to draw text if font supports it otherwise use ASCII.
I did my best to exempt some of the bigger aligned blocks from the reformatting
using the /* clang-format off */ and /* clang-format on */ tags. Probably some
that shouldn't have been formatted were anyway; if you encounter them, please
fix.
The clang-format tags were left in on the basis that it's much easier to prune
those out later than to put them back in, and it means that, modulo my custom
version of clang-format, I should be able to run clang-format on the source tree
again without changing anything, now that Pat has fixed the VA_DECL issues.
