[use] Update to draft spec from Andrew Glass from August 2015

src/hb-ot-shape-complex-use-machine.rl

diff --git a/src/hb-ot-shape-complex-use-machine.rl b/src/hb-ot-shape-complex-use-machine.rl
index f028f38..f6b814b 100644
--- a/src/hb-ot-shape-complex-use-machine.rl
+++ b/src/hb-ot-shape-complex-use-machine.rl
@@ -44,7 +44,6 @@
 O	= 0; # OTHER
 
 B	= 1; # BASE
-IV	= 2; # BASE_VOWEL
 IND	= 3; # BASE_IND
 N	= 4; # BASE_NUM
 GB	= 5; # BASE_OTHER
@@ -96,11 +95,11 @@
 final_consonants = FAbv* FBlw* FPst* FM?;
 
 virama_terminated_cluster =
-	R? (B | GB | IV) VS?
+	R? (B | GB) VS?
 	consonant_modifiers
 	H
 ;
-consonant_cluster =
+standard_cluster =
 	R? (B | GB) VS?
 	consonant_modifiers
 	medial_consonants
@@ -108,13 +107,6 @@
 	vowel_modifiers
 	final_consonants
 ;
-vowel_cluster =
-	R? (IV) VS?
-	consonant_modifiers
-	medial_consonants
-	vowel_modifiers
-	final_consonants
-;
 
 broken_cluster =
 	R?
@@ -134,8 +126,7 @@
 main := |*
 	independent_cluster			=> { found_syllable (independent_cluster); };
 	virama_terminated_cluster		=> { found_syllable (virama_terminated_cluster); };
-	consonant_cluster			=> { found_syllable (consonant_cluster); };
-	vowel_cluster				=> { found_syllable (vowel_cluster); };
+	standard_cluster			=> { found_syllable (standard_cluster); };
 	number_joiner_terminated_cluster	=> { found_syllable (number_joiner_terminated_cluster); };
 	numeral_cluster				=> { found_syllable (numeral_cluster); };
 	symbol_cluster				=> { found_syllable (symbol_cluster); };