v0.5.0

• The macro @pt can be used to print tables with global configurations. Those configurations can be set by the macro @ptconf.
• There is now the option nosubheader to suppress printing sub-headers. This can be useful when printing DataFrame or Dict and it is desired to hide the types of the columns. (Issue #14)
• PrettyTables.jl is now compatible with Tables.jl 0.2. It means that if an elements that is passed to pretty_table is not one of those natively supported, then it will call Tables.columns to automatically convert it. If it fails, than Tables.jl will throw an error instead of PrettyTables.jl. (Issue #13)
• If only one highlighter is wanted, then an instance of Highlighter can now be directly passed to the keyword highlighters, i.e. it does not must be a Tuple anymore.