Fix PDL::Graphics::PGPLOT::Window POD

The docs for the lines() method were incorrect
which triggered a bug with PDL::NiceSlice.  Correcting
the docs is a workaround for the bug which will be
fixed separately.  This should allow tests to pass
for all win32 platforms.
Merge branch 'master' of ssh://pdl.git.sourceforge.net/gitroot/pdl/pdl