Release v0.5.0 · andrey-zherikov/argparse

Enhancements

NamedArgument UDA can be used without parentheses:

@NamedArgument  string a;
@(NamedArgument.Required()) int b;

TrailingArguments UDA can be used without parentheses:
```
@TrailingArguments string[] args;
```
Argument names can be listed without putting them into an array:
```
@NamedArgument("a","apple","appl") int apple;
```
New Placeholder property that can be used with NamedArgument and PositionalArgument UDAs to indicate the value of the argument in help message:
```
@NamedArgument  string s;
@(NamedArgument.Placeholder("VALUE"))  string p;
```
This is how it looks on help page: -s S and -p VALUE
Added validation of the values for enum types. In case if the incorrect value is passed, this message will be printed:
```
Error: Invalid value 'kiwi' for argument '--fruit'.
Valid argument values are: apple,pear,banana
```
Added *NumberOfValues properties to specify number of values that an argument can receive (see readme for details):
```
@(NamedArgument.NumberOfValues(1,3)) int[] a;
@(NamedArgument.NumberOfValues(2))   int[] b;
```
Added AllowedValues property to specify the values that an argument can receive (see readme for details):
```
@(NamedArgument.AllowedValues!(["apple","pear","banana"])) string fruit;
```

HelpText is renamed to Description:

@(NamedArgument.Description("some description"))  string a;