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.