shortenStrings: Shorten a string to a maximum length and indicate shorting by appending '..'
Description
Some axis labels are sometimes just too long and printing them will either
squeeze the actual plot (ggplot) or make the labels disappear beyond the margins (graphics::plot)
One ad-hoc way of avoiding this is to shorten the names, hoping they are still meaningful to the viewer.
If shortened strings are not discernible any longer, consider the short version valid (not the default), otherwise (default) return the full string (--> no-op)
Value
A vector of shortened strings
Details
This function should be applied AFTER you tried more gentle methods, such as delLCP or simplifyNames.