Make API jar available via Maven repository

[berndmoos]

To make it easier and more transparent for other projects to deploy a ZuMult application.

See also: Exmaralda-Org/exmaralda#388

[berndmoos]

N.B.: If the jar is available via Maven, I think that the POM that goes along with it can specify all the transitive dependencies. So a project building on the API (like zumulttgdp) will not have all those dependencies in its own POM. Makes sense?!
The plan would now be to publish the jar in a MAVEN conformant manner via GitHub. Not doing this before a more elegant solution has been found for Exmaralda-Org/exmaralda#388. The difference will be that this API is not built with Ant, but with Maven. Could make things easier or more confusing...

[berndmoos]

Added a <distributionManagement> element to the pom. In order for this to work, there needs to be a GitHub authentication token specified in Maven's settings.xml. The following command will then make a distribution package:

mvn clean package
mvn deploy

The package is then listed on the GitHub page:

https://github.com/zumult-org/zumultapi/packages/2338653

[berndmoos]

Seems to work all right, but it includes many dependencies that are probably not needed.

[berndmoos]

Excluded solr and wordnet dependencies. Much smaller now.