Make it possible to have collection types for positional arguments

[lecode-official]

When using positional arguments, it is sometimes helpful to have the possibility to add a list of values, e.g. consider the following command line arguments:

compile file01 file02 file03

In order to achieve this right now, one would have to use a named argument like so:

compile --files file01 file02 file 03

In order to achieve this there should be an option to specify how many values for a positional argument are expected. The default should be 1, but users could specify any integer greater than 1. Also there should be the option to specify that any number of values greater than 1 are expected, but this should be restricted to a single positional argument. There must not be two positional arguments with an arbitrary number of arguments as this would be ambiguous while parsing.

[lecode-official]

The algorithm should start retrieving all elements from the queue, which are not flag parameters, named parameters, or commands at the beginning of the parsing process. Since every positional argument must have at least one value, the number of these values must be at least the same as the sum of the number of values each positional argument has (if one has an arbitrary number of values, then this should count as 1).

Now there would be two cases: either there is no positional argument with an arbitrary number of values or there is one. If there is no positional argument with an arbitrary number of values, then the parsing is easy: each argument has to receive the number of values it specified.

If there is one positional argument, then there are three possibilities, either it is the first, the last, or one in the middle. If it is the first positional argument, then the sum of values of the rest of the positional arguments has to be removed from the end of the list of parsed values, the rest of the values are assigned to the positional argument with an arbitrary number of values.

If it is the last, then the sum of the number of values of the other positional arguments have to be removed from the beginning of the list of values and the remaining values are assigned to the positional argument with an arbitrary number of values.

If it is in the middle, then the sum of the number of values of the positional arguments before it have to be removed from the list of parsed values, then the sum of the number of values of the positional arguments that come after it have to be removed from the list of parsed values. Finally the remaining values can be assigned to the positional argument with an arbitrary number of values.