How to handle positional arguments

Currently the only way to pass values is via parameters. Explore the option for positional parameters. Here a very early draft:

[commands.build]
script = "build some file %{0}"

As numbers are not allowed for parameter names they can be used to reference to a positional argument. To give more context to an argument:

[commands.build]
script = "build some file %{0}"
arguments = [
  { name = "file", description = "Something nice" } # Relates to %{0} 
]

Defined options are:

name - A name that will appear when calling the help via litr --help as string.
description - A description that will appear when calling the help via litr --help as string.
type - The default type is "string". This can be an array of strings to define possible options. Needs to be further defined in #8

krieselreihe / litr