Rename use{Division,Multiplication}Symbol options

...to be more specific about when these symbols are being used (also,
it's called \times not \multiplication)
diff --git a/src/commands/math.js b/src/commands/math.js
index 82f5374..bc876c6 100644
--- a/src/commands/math.js
+++ b/src/commands/math.js
@@ -402,9 +402,9 @@
       return Letter(ch);
     else if (/^\d$/.test(ch))
       return Digit(ch);
-    else if (options && options.useDivisionSymbol && ch == '/')
+    else if (options && options.typingSlashWritesDivisionSymbol && ch === '/')
       return LatexCmds['÷'](ch);
-    else if (options && options.useMultiplicationSymbol && ch == '*')
+    else if (options && options.typingAsteriskWritesTimesSymbol && ch === '*')
       return LatexCmds['×'](ch);
     else if (cons = CharCmds[ch] || LatexCmds[ch])
       return cons(ch);