pxmake 0.17.0

Bug fixes and minor improvements

• Remove import of 'pillar' package. (#387)
• Fix various issues with CONTVARIABLE. (#364 #386)
• px_data() updates metadata to match new data frame. (#385 #396 #399)
• When adding more languages dummy values are added as VALUES instead of blanks.
• Throw error when using px_save() on a px object that contains duplicates in
  the data table. (#402)
• Don't save NA values in aggregations files. (#401)

Breaking changes

• Create aggregations from texts in section [Aggtext]. (#389)