Attempt to merge ords together

Summary:
Try not to waste spans by putting a bunch of numbers or letters
together into the same ord box. I don't think that this breaks any of the
current stuff.

Test Plan:
Write lots of expressions that have ords in them. Make sure that all
the reasonable ords are grouped together, and that the formatting still works.

Reviewers: spicyj

Reviewed By: spicyj

Differential Revision: http://phabricator.benalpert.com/D52

parser.jison

@@ -143,8 +143,10 @@ func
     ;
 
 atom
-    : 'ORD'
-        {$$ = [{type: 'ord', value: yytext}];}
+    : 'TEXTORD'
+        {$$ = [{type: 'textord', value: yytext}];}
+    | 'MATHORD'
+        {$$ = [{type: 'mathord', value: yytext}];}
     | 'BIN'
         {$$ = [{type: 'bin', value: yytext}];}
     | 'REL'