Multiple X vars possible and Summary Level Data

ggquickeda 0.1.8

• Major New Feature! Added possibility to use more than one x variable(s) and or no y variable(s) (useful for summary level viz)
• Added a new vignette: Visualizing Summary Data with ggquickeda
• Added option for an explicit Missing category with custom cuts
• Added option to compute the inverse of Numeric variables (useful to weight by inverse of standard error for example)
• Moved the rounding to after division/inverse (useful for labeling of the plot using data values)
• Added possibility to round data labels before plotting (additional control for rounding labels)
• Added a blank shape type so we can do multiple y(s) when some layers do not have a point plotted.
• Added Docker configuration