[NTG-context] \mathopen, \Uover and friends

[Otared Kavian]

Hi Hans,

Thanks for the quick fix of today's upload. 
I could typeset your examples with \mathopen, \mathclose and these are great features in order to fine tune the spacing in math mode.

Regarding the new command \Uover, I thought maybe it would be more consistent to have the usual structure 
${1} \Uover {2}$ 
like the more friendly ${1} \over {2}$ instead of having
$\Uover{1}{2}$ 
which is more like the \frac structure.

Also a structure like
$\Uover style \textstyle{1}{2}$
seems a little bit far from the usual ConTeXt atmposphere… Would it not be possible to have
${1} \Uover[style=textstyle] {2}$ 
instead?

In any case, thanks a lot for the constant addition of cute features…
Best regards: Otared K.