Write shpdump and tkdump demos

[anoved]

Like dbfdump.tcl, shpdump.tcl is patterned after the shapelib utility. It should simply list the shapefile coordinates.

Tkdump should show the shapefile in a canvas. Use a placeholder Projection() function to map presumed ll coords to screen. At minimum, invert y and increase scale.

Canvas should be scrollable and expand to fit window. Features should be assigned bindings to puts their attr when clicked.