Deploy DM artifacts to Maven Central

[jri]

Crucial work had be done already by Constantin.
The first DM version deployed at Central will be DM 4.4.1

[Jörg Richter <jri@…>]

In f04485047333223c30fbef5c5a94dbfa0719b126/deepamehta:

Adapt POMs for deploying at Maven Central (#713).

For deploying (a snapshot) at Maven Central:

mvn clean deploy -P release

Executable from DM home.

Changes:

• The release profile defines all modules to be deployed.
• Moved <distributionManagement> from Parent POM to Global POM.
• Set Global POM as the parent for both
  • Parent POM
  • Plugin Parent POM

See #713.