patchwork 1.1.0

• Add inset_element() to allow adding plots as insets
• patchwork now supports raster and nativeRaster objects
• Avoid incrementing tag counter when recursing into a nested plot without
  additional tags to use (#147)
• Fix bug that prevented strips turned off with element_blank() from working
  (#200)
• Add option to supply a custom sequence of tags to use for auto-tagging (#211,
  #63)