Modify grammar slighly to simplify parse tree

README

@@ -10,7 +10,7 @@ so here we are.
 This engine is not going to be strictly supporting any standard
 syntax; the expression syntax I intend to support follows.
 
-	regex ::= sequence ( '|' regex )?
+	regex ::= sequence ( '|' sequence )*
 	sequence ::= term+
 	term ::= ( '.' | class | literal | '(' regex ')' ) quantifier?
 	class ::= '[' '^'? literal+ ']'