Parsing arguments with trailing garbage should fail

[mjerabek]

Integer arguments with trailing garbage are successfully decoded instead of giving an error:
42garbage is decoded as 42 instead of parse error

This will be also a problem for other types. I looked at the implementation and the fix should be quite simple -- just checking if the stringstream is empty after the conversion.

[grafikrobot]

Fixed in Lyra library with this change bfgroup/Lyra@cdd5a92