Merge from vendor branch TNF:

Merge from vendor branch TNF:
Import tex-pst-osci-2.82 as graphics/tex-pst-osci.

pst-osci is a PSTricks package enables you to produce oscilloscope
"screen shots". Three channels can be used to represent the most common
signals (damped or not): namely sinusoidal, rectangular, triangular,
dog's tooth (left and right oriented). The third channel allows you to
add, to subtract or to multiply the two other signals. Lissajous
diagrams (XY-mode) can also be obtained.