* Remove DUK_USE_DPRINT_COLORS and the whole colored log feature.
* Add DUK_USE_DEBUG_WRITE() duk_config.h macro to actually write log
entries. Postpone formatting of the message there (except for the
body of the message) so that it can implement coloring etc as needed.
* Also move debug formatting buffer into a stack local rather than a
global to avoid thread issues.
Also remove mostly unused old debug code.
Debug code doesn't have access to 'heap' so it cannot decode pointers.
Cause an #error for now if both debug prints and pointer compression
are enabled at the same time.
Remove duk_debug_hobject.c from make and dist. It was out of date and
not used in practice anymore.
Lots of minor string format cleanups (casts mainly).
Add a special check to detect NULL pointers with %s/%p formats in debug
logging to avoid calling the platform sprintf() with a NULL value. This
is especially important for %s + NULL, which is not portable and may crash
on some platforms. Debug logging will now format these specially as "NULL"
and avoid calling the platform for formatting, so debug log call sites don't
need to be careful with NULL pointers any more.