[fix #743] Change --version and -version options to output EpubCheck version

[kamorrissey]

A minimal set of changes to repurpose the "--version" and "-version" command line options to output the EpubCheck program version instead of being undocumented synonyms for the "-v" option. Made sure to update the --help message.

[kalaspuffar]

Looks good to me. Very straightforward.
I'm not sure if it's required, but there is a class for testing command line features (com.adobe.epubcheck.cli.CLITest)
So a unit test could be crafted for this flag.

[rdeltour]

Looks generally OK to me (thank you!). A couple things however before merging:

The following help text should be updated in message.properties :

version_argument_expected=Version number omitted from the -version argument.

Also, as @kalaspuffar said suggested, could you please add a unit test?

[kmorrissey-mersive]

I'll get to the requested changes this weekend.

[kamorrissey]

I added command line unit tests for version and help.

[rdeltour]

Looks good to me, thank you @kamorrissey! 👍

[tofi86]

All changes approved, awesome! :)

I suggest we ship this with 4.1 and I'm going to merge it to master in a couple of hours, are you all okay with that?

[tofi86]

Merged. Thanks a lot @kamorrissey! 👏 🎉

Looking forward to seeing more contributions from you! 👍