Latex output could be better for some operations

[shashi]

• sin should be \sin
• a^{-1} shows up wrong -- 1 is not even super script. (see a^(b - 1))

cc @alanedelman

[karlwessel]

This seems to be fixed.
SymbolicUtils does not support Latexify. And Symbolics correctly latexifies it:

julia> using Symbolics
julia> @variables x y
2-element Vector{Num}:
 x
 y
julia> using Latexify

julia> latexify(sin(x))
L"\begin{equation}
\sin\left( x \right)
\end{equation}
"

julia> latexify(x^(-1))
L"\begin{equation}
\frac{1}{x}
\end{equation}
"

julia> latexify(x^(y-1))
L"\begin{equation}
x^{-1 + y}
\end{equation}
"