[NTG-context] llap, rlap, clap equivalent for math

Inspired by Alexander Perlis' macros in http://www.tug.org/TUGboat/Articles/tb22-4/tb72perlS.pdf can we have the math equivalent of llap etc. in ConTeXt. Ideally, \llap etc. should be modified so that they work in math mode also (just like \smash and \phantom). If not, we can have the following simple definitions: \def\mathclap{\mathpalette\domathclap} \def\domathclap#1#2{\clap{$\m@th#1#2$}} \def\mathllap{\mathpalette\domathllap} \def\domathllap#1#2{\llap{$\m@th#1#2$}} \def\mathrlap{\mathpalette\domathrlap} \def\domathrlap#1#2{\rlap{$\m@th#1#2$}} Usage: \startformula A = \sum_{\mathclap{1 \le i \le N}} a_i \stopformula Aditya