Updated plotchart work with latest from release and trunk.
Implementing the options -timeformat and -gmt for the x-axis as per bug 3613718
Correct some formatting errors in the documenation
Added example for stripchart with date/time; updated version and change log
Updated plotchart work with latest from release and trunk.
Removed leftover print statements
Merge implementation of subtitles, extended and corrected tests, options -timeformat and -gmt
Correct the version number - there was a difference between that in pkgIndex.tcl and that in plotchart.tcl (reported on clt)