[NTG-context] counter for MPtoPDF calls [feature request]

[Peter Rolf]

Hi Hans,

I tested the beta from yesterday and I liked the incremented number
behind the MPtoPDF calls (in older versions this was always [1]). I'm
currently optimizing some of my graphics for trailtypesetting and the
incremented counter was really informative.

[..]
[MP to PDF] (./testbed-mpgraph.1)This is MetaPost, Version 0.901 (Web2c
7.5.3)
(testbed-mpgraph.mp (r:\mp-test.mp) [37]
                                    ^^^^
[..]

In the current beta this number is completely missing. What was this
number for and is it possible to attach the current number of MPtoPDF calls?

Greetings, Peter