TeXMath reader: always return Open with \left, Close with \right.
Unicode.ToTeXMath: export getSymbolType.
Fixed compiler warning
TeXMath reader:  Fixed bug in tilRight.

Now we can correctly handle delimited sections with \left. and \right.
MathML reader:  determine correct symbol type for symbols.

Previously we defaulted to ESymbol Op (ESymbol Ord would have been
a better default).  Now we use getSymbolType from Unicode.ToTeXMath
to determine the symbol type, if the MathML dictionary doesn't tell
us.
Updated tests.