[NTG-context] ' undefined inside \startformula .. \stopformula

[Sanjoy Mahajan]

I just noticed this test file failing:

\starttext
$f'(x)$
\startformula
f^\prime(x)\quad f'(x)
\stopformula
\stoptext

It gives:

! Undefined control sequence.
l.4 f^\prime(x)\quad f'
                       (x)

As you can see from lack of complaint about $f'(x)$, the ' still works
in inline math mode.  So somehow the ' active charcode setting didn't
make it into display-math mode?

I couldn't get any tests to produce a PDF file on the live context, so I
didn't test it there.  But I'm using:

ConTeXt  ver: 2006.12.20 23:52 MK II  fmt: 2006.12.25

-Sanjoy

`A nation of slaves is always prepared to applaud the clemency of their
 master who, in the abuse of absolute power, does not proceed to the
 last extremes of injustice and oppression.'  (Gibbon)