Handle nested <math> elements without error.  Resolves issue #614.
Add phasorangle notation to menclosed.  Resolves issue#561.
Fixed default value for mo@symmetric.  Resolves issue #469.
Put checking for screenX into try...catch for IE8 (grr).  Resolves issue #348.
Merge branch 'issue614' into develop.  Issue #614.
Merge branch 'issue561' into develop.  Issue #561.
Merge branch 'issue469' into develop.  Issue #469.
Merge branch 'issue348' into develop.  Issue #348.