Change hb_shape() API back to what it was, add hb_shape_full()

I disliked changing hb_shape() API, and disliked the fact that it was
returning a bool now.  So, reverted.  Added new API for the extra
functionality.

src/hb-view.cc

diff --git a/src/hb-view.cc b/src/hb-view.cc
index 67070ef..dc3fc47 100644
--- a/src/hb-view.cc
+++ b/src/hb-view.cc
@@ -370,7 +370,7 @@
     len = strlen (utf8);
   hb_buffer_add_utf8 (hb_buffer, utf8, len, 0, len);
 
-  hb_shape (hb_font, hb_buffer, features, num_features, NULL, NULL);
+  hb_shape (hb_font, hb_buffer, features, num_features);
 
   num_glyphs = hb_buffer_get_length (hb_buffer);
   hb_glyph = hb_buffer_get_glyph_infos (hb_buffer, NULL);