added 'c' option to install packages
added 'c' option to install packages

currently treating subsequent packages as options
emunozh/spatial-microsim-book,Robinlovelace/spatial-microsim-book,Robinlovelace/spatial-microsim-book,richardellison/spatial-microsim-book,richardellison/spatial-microsim-book,modumont/spatial-microsim-book,majazaloznik/spatial-microsim-book,modumont/spatial-microsim-book,Robinlovelace/spatial-microsim-book,emunozh/spatial-microsim-book,modumont/spatial-microsim-book,jojo-/spatial-microsim-book,majazaloznik/spatial-microsim-book,jojo-/spatial-microsim-book