Fixed URLs
Ensured suggested packages appear only conditionally everywhere.
updated examples, documentation, and vignettes to not rely on the Rgraphviz package from Bioconductor. Also added some information
for the user to install this package if they want to draw any of the graphs constructed by zenplots
fixed link to graphNEL from graph package in documentation of graph_pairs.
added mvtnorm, crop to suggests in DESCRIPTION for demo; also made explicit calls to
crop::dev.off.crop() in SP500 demo.
zenplots package documentation file
zenplot now (invisibly) returns a list with two extra classes
zenplot to identify that the structure is a zenplotzengraphics, zenGrid, or zenLoon to indicate which graphics
package was used.loon zenplots to be turned into ggplots via package loon.ggplotdocumentation updated accordingly.
updated documentation on zenpath to mention that pairs must describe
a connected graph.