Make LINK_EXTENSION and FILE_EXTENSION configurable about marklet

[Faylixe]

We can introduce an command line parameter to set the target output link maybe ? With .md as default one

[trieloff]

Either a command line parameter or a Java system property. I need to look what feels more natural for Javadoc doclets. Agree on the default, we should go back to the 1.0.5 behavior.

[Faylixe]

There is a specific command line processing API for doclet (see validOptions() and optionsLength() on Marklet.java) which can be used more easily than system properties I think. That way we can set a Singleton configuration with runtime parameters such as File / link extension.

[Faylixe]

Just checked out the code and turns out you already have implements options for file extension (-e) and link extension (-l) with .md as default value for both :)

[Faylixe]

@trieloff I fixed MarkletOptions#optionLength(String) method which didn't take in account new introduced option. Will published new version tomorrow. I plan to introduce unit testing / integration testing in order to ensure doclet is valid through CI before to publish into central.

[trieloff]

Nice! Thank you.