RFR: 7362: Reference wrong in agent plug-in.xml

[Marcus Hirt]

Also cleaning up and making it possible to use the project from within Eclipse.

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Commit messages:
 - 7362: Reference wrong in agent plug-in.xml

Changes: https://git.openjdk.java.net/jmc/pull/283/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=283&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7362
  Stats: 100 lines in 13 files changed: 49 ins; 47 del; 4 mod
  Patch: https://git.openjdk.java.net/jmc/pull/283.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/283/head:pull/283

PR: https://git.openjdk.java.net/jmc/pull/283