RFR: 7903589: JOL: Rework and amend CLI tools [v2]

[Aleksey Shipilev]

> CLI tools need a few touchups. Heapdump utilities, notably, need more work.

Aleksey Shipilev has updated the pull request incrementally with two additional commits since the last revision:

 - More README updates
 - Cleanups

-------------

Changes:
  - all: https://git.openjdk.org/jol/pull/55/files
  - new: https://git.openjdk.org/jol/pull/55/files/37ad194e..8649f114

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jol&pr=55&range=01
 - incr: https://webrevs.openjdk.org/?repo=jol&pr=55&range=00-01

  Stats: 75 lines in 4 files changed: 53 ins; 16 del; 6 mod
  Patch: https://git.openjdk.org/jol/pull/55.diff
  Fetch: git fetch https://git.openjdk.org/jol.git pull/55/head:pull/55

PR: https://git.openjdk.org/jol/pull/55