RFR: JDK-8290011: IGV: Remove dead code and cleanup [v15]

[Tobias Holenstein]

> Remove dead code from the IGV code base. There are many unused or redundant functions in the code

Tobias Holenstein has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 49 commits:

 - Merge remote-tracking branch 'origin/master' into JDK-8290011
 - merge current master
 - Merge remote-tracking branch 'origin/master' into JDK-8290011
 - fix imports after merge
 - Merge remote-tracking branch 'origin/master' into JDK-8290011
 - Undo removal of toString() in Group.java
 - make fond constants uppercase
 - more code cleanup
 - style update 2
 - delete unused Graph.java and Edge.java
 - ... and 39 more: https://git.openjdk.org/jdk/compare/3b476a17...7faec1a5

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Changes: https://git.openjdk.org/jdk/pull/10197/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10197&range=14
  Stats: 4759 lines in 137 files changed: 344 ins; 3602 del; 813 mod
  Patch: https://git.openjdk.org/jdk/pull/10197.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10197/head:pull/10197

PR: https://git.openjdk.org/jdk/pull/10197