loon 1.3.1

Added new functions l_loonWidgets() which returns widgets of all
displayed loon plots. Related functions include
- l_basePaths() and l_compoundPaths
- l_getFromPath()
Fixed bug so that l_make_glyphs() again works in Mac OS Catalina
(Thanks to Brian Ripley and Simon Urbanek)
- Cool new example there which produces the Periodic Table of the Elements
  as a scatterplot (data "elements" from loon.data package).
  Actually see the periodicity by brushing.
A minor bug fix with respect to facet label layout
"color", "size", "linewidth", "glyph", added to 'l_userOptions()'
- default "color", "size", "linewidth", "glyph", etc. now set to
  look up default 'l_getOption("linewidth")' etc.
- this allows the user to change the default look of all plots
  simply by using 'l_setOption("color", "black")' for example.

loon 1.3.0

several new features added to loon plots
- NAs are now accommodated
- histograms recognize factors to produce barplots
group by and facetting in loon plots
- l_plot() and l_hist() now accept arguments by and facet
improved docuentation
- new vignettes
- better organized reference manual via l_web()
in some OSes the function l_image_import_files() has stopped working
- seems to be a problem with the tcltk function tkimage.create()
- tkimage.create() function works on older .png files but seemingly not
  on newer ones
- l_make_glyphs() calls l_image_import_files() and so although it will still create the necessary png files, it may fail to read them back in.
- the problem has been observed (unreliably) to work if the png is further processed outside R.
- so demo("l_make_glyphs") has been removed

deprecated l_saveStatesRDS()
- replaced by l_saveStates
- reasoning for name change is to have the same name be used in
  the Python release for the same functionality
- introduced l_getSavedStates() to read the states (instead of readRDS for the
  same reason as above).
updated l_cget()
- Fixed reading of labels to retrieve raw characters so that braces etc. can appear in labels
- updated l_hist.factor so that a layer of factor level labels appear below the corresponding bar

added l_saveStatesRDS()
- saves named or all states to disk for later retrieval (e.g. in Rmarkdown)
added l_copyStates(source, target)
- copies the info_state values of source to that of target.
- some basic states are excluded but can be overridden.