command 0.3.0

Variable-length file arguments

Added cmd_assign_collect() and cmd_assign_collect_quiet(), which assign every unnamed command-line argument to the one argument that was not passed by name.
extract_make(), extract_shell(), makefile(), and shell_script() read calls to cmd_assign_collect(). A character vector of paths becomes one file name per element, and in a Makefile the last element is the target.
extract_make(), extract_shell(), makefile(), and shell_script() now recognize cmd_assign_quiet(), cmd_assign_collect_quiet(), and a call written with a command:: or command::: prefix.
The dot-name convention for file arguments has been documented in the help for cmd_assign() and cmd_assign_collect().
shell_script() orders commands by matching output paths with input paths.
cmd_assign() and cmd_assign_collect() reject a named command-line argument that is passed more than once.
makefile(), shell_script(), extract_make(), and extract_shell() read literal values from calls. A name or a function call such as file.path() or paste() is an error.

A named argument is split on the first =, so the value may itself contain =. An argument with an empty name, such as --=value, is an error.

extract_shell() and shell_script() leave a plain length-1 vector unchanged, and quote a path or value only when it contains a space or a character that is special to the shell. NULL is written as --name=NULL.
shell_script() rejects a quiet value that is not TRUE or FALSE.

Empty command line values like --v= (from an undefined Make variable) are now an error unless the corresponding cmd_assign() argument is character
When an empty string is assigned, the message notes that the value is an empty string

extract_make() and extract_shell() no longer prefix relative paths with ./

Added use_renv(), which activates a renv project at the start of scripts run with Rscript (which skips .Rprofile).
Added article “Using command with renv”

Tidied articles, and added detail on the way that extract_make() and extract_shell() treat dotted vs non-dotted arguments.

Fixed bug in extract_shell(), extract_make(), shell_script(), and makefile() where the shell commands or Makefile rules created by these function used absolute paths to R scripts, rather than relative paths.