We don't use gthread anymore, remove leftovers.

As reported by Peter Breitenlohner:

I think this is a very bad idea because ENV is used to specify a startup
file to be read by some/all shells.

Fails now.  Fixing.

New shaping testsuite and framework coming.

Remove hb_ft_get_font_funcs() as it cannot be used by the user anyway.

Add hb_ft_font_set_funcs().  Which will make the font internally use
FreeType.  That is, no need for the font to have created using the
hb-ft API.  Just create using hb_face_create()/hb_font_create() and
then call this on the font (after having set font scale).  This
internally creates an FT_Face and attached to the font.

Needs fonts to be put in test/fonts.  Tests are skipped otherwise.
Run with --verbose for details.  Working on improving the test runner
to make it easier to make sense of what's going on.

Shows undocumented symbols.

Caught by "make check-valgrind".

Adds check-valgrind among other modes.  We do not run under gtester by
default anymore.

We're not at 100% coverage yet, so do not enable the test by default.

I'm in awe with how many bugs this test revealed.  All fixed.

Now the test/object test deadlocks as expected.  Fix coming.

Step version up to 0.5.0.

Also, fix to pass "make distcheck"

Revealed many bugs in the (untested and known buggy) user_data
support.

Wraps around glib for convenience and ease of use.

Unicode data providers can now be subclassed, including support for
chain-up.  The interface should now be nicely bindable, as well.

Also fix glib unicode funcs that where broken after hb_script_t
changes.  Nicely caught by the test-unicode.c added in this commit.

Uses the glib testing framework.  Wrote unit tests for hb-common.h
types.