0.2.4

factor levels remain sfheaders issue 89

0.2.2

removed C++ system requirements

0.2.1

updated C++ dependencies
nest_impl() function for nesting & un-nesting lists

0.2.0

user can add closed attribute added to shapes if the first row is repeated at the end of a matrix
nest.hpp - re-enabled
columns.hpp - templated column_positions() and handles data.frame inputs