[Rd] pictex should quote underscores (PR#8725)

[sds at gnu.org]

Full_Name: Sam
Version: 2.2.1, 2005-12-20
OS: i686-redhat-linux-gnu
Submission from: (NULL) (209.213.205.130)


running
     pictex()
     plot(1:11,(-5:5)^2, type='b', main="Simple_Example_Plot")
     dev.off()
(as in the pictex example, but with underscores instead of spaces).
the TeX file contains

\put {Simple_Example_Plot}  [lB] <0.00pt,0.00pt> at 124.00 275.33

the underscores have a special meaning in TeX, so they should be quoted
or converted to dashes.