Removed unused code.

Unused variables are now reported natively by JSLint.
Pass a Function to the JSLint constructor.

This slightly simplifies the code as it means that you don't have to do
this throughout.
Seal standard objects again.
Use Context.emptyArgs where possible.
It's a bad idea to seal before reading in JSLint.

In fact, sealing doesn't buy us much anyway, so just remove it.
Correct the include/exclude docs.

We need to mention that a sub element is required.
Fix docs: replace "undef" option with "es5".
Reimplement --help, to get it each option on one line.

JCommander is quite unhelpful here.
Update sample --help output.
Update to JSLint 2013-05-06.
Update release notes.
issue 95: read stdin if "-" is passed as a filename.
[maven-release-plugin] prepare release rel-2.0.5