wc command should be compliant with posix ones

The Posix wc command formatting is not fully correct. For instance, a simple:

echo "foo\nbar"|wc -l

displays:

       2     2

So the output formatting is not correct (result is displayed twice) and wc can't be easily used in scripting.

To be compliant with standard Posix wc command, the output should be:

2

I'm adding tests and fixes.