Add keyword arguments to Sprintf, similar to Python's .format()

[webvictim]

In Python, you can use keywords and numbers in format() to refer to the same part of a string for replacement - see https://www.digitalocean.com/community/tutorials/how-to-use-string-formatters-in-python-3#reordering-formatters-with-positional-and-keyword-arguments

You can probably do the same thing in Go, I just don't know how.

It would be useful to have similar functionality in Force too, so that rather than needing to repeat the same argument multiple times:

Sprintf("%s %s %s %s", "banana", "banana", "banana", "cabbage")

We could do things like:

# named references
Sprintf("{one} {one} {one) {two}", one="banana", two="cabbage") # prints "banana banana banana cabbage"

# numbered references
Sprintf("{0} {0} {0) {1}", "banana", "cabbage") # prints "banana banana banana cabbage"

# or maybe the ultimate, more Force-like structure...
Sprintf("{s.One} {s.One} {s.One} {s.Two}", struct s{One: "banana"; Two: "cabbage"}) # prints "banana banana banana cabbage"

This is perhaps easier in Python because of its duck typing.

[klizhentas]

Sprintf("{s.One} {s.One} {s.One} {s.Two}", _{One: "banana"; Two: "cabbage"}) 

This should be possible to do

[webvictim]

That would be super cool.