https://github.com/behdad/harfbuzz/issues/506

Before, that was printed using --debug (and in both hb-shape and hb-view).
Changed it, now hb-shape has a new command-line argument called --show-messages.
When invoked, it also respects other output formatting options.  The messages
are better formatted and printed to te same place that hb-shape output is
directed to.  Previously they were written to stderr.

Fixes https://github.com/behdad/harfbuzz/issues/506

Is hooked up to the font, but not to FreeType, so raster doesn't show yet.

Documentation needs to be done.

The latter doesn't seem to be available in Cygwin.  I'm surprised it
compiled before...

Use the fallback implementation for lround() only on pre-2013 Visual
Studio, and ensure we are clear about the types of the parameters for
lround() and scalbnf(), since Visual Studio can be quite picky on
ambiguous parameter types.  Also, use g_ascii_strcasecmp() rather than
strcasecmp() as we are already using GLib for this code and we are
assured that g_ascii_strcasemp() is available.

For scalbnf() on pre-2013 Visaul Studio, a fallback implementation is
needed, but use another forced-included header for those compilers, which
will be added later.

Also use (char)27 on Visual Studio builds as '\e' is not a recognized
escape sequence, which will do the same thing.

This has the effect that the font data will end up in a memory
section malloc()ed exactly to its size.  This gives us better
valgrind detection of out-of-bounds access.

Previously, the font data was placed in a mmap()ed section or
GString-allocated area, which didn't have proper protections
at the end when running under valgrind.

New API: HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS

hb-shape now accepts --show-extents.

Patch from Simon Cozens.

TODO: Documentation.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=71445

Applies to --font-size and --margin.

Hopefully the scanf usage here doesn't have compatibility issues
(star being counted in the return value, etc).

Remove reference to --help-output-content in --help-output (as --help-output-format's options aren't available in hb-view)

Also makes hb-view to use 8 bits of subpixel precision and shape at
requested size, instead of always shaping at upem and scaling results.

Fixes https://github.com/behdad/harfbuzz/pull/74

Supports ft and ot right now.  hb-view currently not rendering with ot.
Will fix after some clean up.

Avoids "deprecated" warnings.

Was introduced in glib 2.22.

Useful for profiling shapers.

As reported by Jonathan, OS X has setmode() that is something other
than what setmode() is on Win32.  So, limit invocation to Windows
platforms only.

Thanks to Khaled for spotting it.

Now, it looks like this breaks Cygwin again.  Have to figure out what's
going on.

Looks like Cygwin / MSVC declare it that way, and it still works on
MinGW32 cross.

Two output formats for now: TEXT, and JSON.  For example:

  hb-shape --output-format=json

Deserialization API is added, but not implemented yet.

Use with Arabic, for example, to see the effect on joining.