Features introduced in 5.0
-  Terminal independent dash types.
-  The default sequence of colors used for successive elements in a plot is
 more easily distinguished by users with color-vision defects.
-  New plot types with parallelaxes, with table.
-  Hypertext labels activated by a mouse-over event.
-  Explicit sampling ranges in 2D and 3D function plots and pseudofiles
 '+' and '++'.
-  Plugin support through new command import that attaches a user-defined
 function name to a function provided by an external shared object.