Right now it checks for monotone cluster values.  Other checks to be added.

Not all shapers code is updated to set this properly.
GSUB and Arabic shaper are updated.
GPOS and other shapers are NOT.

Fixes https://github.com/behdad/harfbuzz/issues/224

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

Coverity ID: 141042

New API: HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS

hb-shape now accepts --show-extents.

Patch from Simon Cozens.

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.

Useful for benchmarking, to avoid buffer serialization overhead (which
seems to by far dominate shaping!)

Add deprecated alias for old name.

https://bugs.freedesktop.org/show_bug.cgi?id=65544

If you say:

  hb-shape font.ttf text --output-file out.txt

This was previously failing:

  Unknown output format `txt'; supported formats are: TEXT / JSON

Now we simply fallback to TEXT if no explicit format was requested.

And list supported formats.

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

  hb-shape --output-format=json

Deserialization API is added, but not implemented yet.

Also fix cairo cluster generation.

Ok, much more useful as a test suite driver now.

Like hb-view, but prints out buffer contents.

The output format is kinda cryptic.  Suggestions welcome.

Now we can use the same code to do other utils...

This reverts commit 80af2812, reversing
changes made to c442672e.

This reverts commit c939f6aff405ca7b10b1f1538f46148bff719fcb.