Ignore `replot` command called from mouse/hotkey-event-enhanced...
allow setting arrow head(s) sizes --- new keywords `heads` and...
avoid writing filenames in keys as enhanced text in enhanced-text capable terminals (postscript and Presentation Manager)
bugfix 'if ((*t->pointsize))' changed to 'if (t->pointsize)'
added documentation for the 'history' and 'system' commands
post.trm: fixed /h definition for pm3d's gray palette
color.c, pm3d.c: allow pm3d compile without pslatex
make the branched version compile under OS/2