v0.19.3

• fixed a bug in deprecation code for when setindex! was passed a 1-row DataFrame as the right hand side (note though this syntax is not recommended to be used);
• DataFrameRows and DataFrameColumns now support getproperty and propertynames and have a custom printing that shows them similarly like data frames
• categorical and categorical! now accept Type as cols argument, so that the user can flexibly decide which columns are converted to categorical based on their type
• columnindex function from Tables.jl is now exported
• All and Between can now be used for indexing columns of a data frame
• passing a Tuple as a on keyword argument is deprecated (use Pair instead)
• minor documentation and build system improvements