Xpose 4.2.1 released

* Changed the behaviour of xpose.multiple.plot.default. Now
multiple plots are returned as objects just like single plots are
(no automatic printing from the function that created the plot
list). This is accomplished by defining a new class -
xpose.multiple.plots - and corresponding print and show methods for
that class.
* Updated xpose.VPC, xpose.VPC.categorical and xpose.VPC.both to
handle the new format of PsN vpc_results.csv
files.
* see changelog for more details
https://sourceforge.net/projects/xpose/files/Xpose4/Xpose_4.2.1/changelog.txt/view