TeXUtilities#toTeX() method returns non optimal TeX frac{}{} expression.

[Axel Kramer]

TeXUtilities#toTeX() method returns non optimal TeX frac{}{} expression.

Example: (ad+bc)d^(-1)f^(-1)

should be transformed to \frac{b\,c + a\,d}{d\,f}

[Axel Kramer]

See commit https://bitbucket.org/axelclk/symja_android_library/commits/1488b8ac6b2eb54bc3fa33ef432e6d7bd69821e8