%.f fails with unexpected placeholder

[daurnimator]

https://github.com/fengari-lua/fengari/issues/147

C language docs says the following about .precision field in sprintf() format:

If the period is specified without an explicit value for precision, 0 is assumed.

$ node
> require("sprintf-js").sprintf("%.f", 2)
Thrown:
SyntaxError: [sprintf] unexpected placeholder
> require("sprintf-js").sprintf("%.0f", 2)
'2'

[ashwalk33r]

PR with fix https://github.com/alexei/sprintf.js/pull/188