Instead of maintaining a single sparse table mapping Unicode to the
currently selected code page, we now maintain a collection of such
tables mapping Unicode to any code page we've so far found a need to
work with, and we add code pages to that list as necessary, and never
throw them away (since there are a limited number of them).
This means that the wc_to_mb family of functions are effectively
stateless: they no longer depend on a 'struct unicode_data'
corresponding to the current terminal settings. So I've removed that
parameter from all of them.
This fills in the missing piece of yesterday's commit a216d86106:
now wc_to_mb too should be able to handle internally-implemented
character sets, by hastily making their reverse mapping table if it
doesn't already have it.
(That was only a _latent_ bug, because the only use of wc_to_mb in the
cross-platform or Windows code _did_ want to convert to the currently
selected code page, so the old strategy worked in that case. But there
was no protection against an unworkable use of it being added later.)
marshal.h now provides a macro put_fmt() which allows you to write
arbitrary printf-formatted data to an arbitrary BinarySink.
We already had this facility for strbufs in particular, in the form of
strbuf_catf(). That was able to take advantage of knowing the inner
structure of a strbuf to minimise memory allocation (it would snprintf
directly into the strbuf's existing buffer if possible). For a general
black-box BinarySink we can't do that, so instead we dupvprintf into a
temporary buffer.
For consistency, I've removed strbuf_catf, and converted all uses of
it into the new put_fmt - and I've also added an extra vtable method
in the BinarySink API, so that put_fmt can still use strbuf_catf's
more efficient memory management when talking to a strbuf, and fall
back to the simpler strategy when that's not available.
This gets rid of all those annoying 'win', 'ux' and 'gtk' prefixes
which made filenames annoying to type and to tab-complete. Also, as
with my other recent renaming sprees, I've taken the opportunity to
expand and clarify some of the names so that they're not such cryptic
abbreviations.
