patchwork 1.1.3

• NULL can now be used with the different arithmetic operators and will result
  in a non-operation (i.e. the non-null part will be returned unmodified) (#290)
• Fix a bug that prevented plots with multi-level strips from being merged
  together (#277)
• Patchworks will now render correctly when unserialised in a fresh session,
  providing the patchwork package is available (#242)
• Fixed a bug preventing faceted plots with strip placement outside the axis
  from being aligned (#325)
• Fixed a bug that let to inconsistent results when combining fixed aspect plots
  in different order (#274)
• Fixed a bug that prevented nested patchworks with empty columns or rows at the
  bottom or to the right to be inserted into a layout (#273)
• Patchwork objects now behaves more correctly like an unnamed list of ggplots.
  This makes View() work on them (#317), and allow one to use length() to
  determine the number of patches in a patchwork (#293)
• Expressions and calls can now be used as plot annotations in the same way as
  they can be used for titles in ggplot2 (#295)