Added data set labels
Added black and grey color parameters
Removed lines-points from set of "Plot Elements"
Parameterized data functions
renamed points to symbols

The word "symbols" is a more precise description of the graphical
elements used than "points". (The "points" or "point" can also be
interpreted as an abstract geometric or algebratic quantity.)
Replaced meta-data and its derivatives with <-meta-data, etc
Switching back to use of "points" instead of "symbols"
Added injection operators <-pairs and <-lists to export list
Removed lines-points from export list

This is not longer defined.
BUG FIXES: Errors in data injection implementations
Renamed <-pairs to <-

The expectation is that <-pairs will be used frequently, and <-
will save some typing.
Renamed <-lists to <-zip-
Fixed high level plot functions per recent name changes