RFR: Cleanups: README typos and links, .gitignore, leftover JDK migrations, column widths [v2]

[Sergey Ponomarev]

> Some non critical changes:
> 1. Currently the repo has `.hgignore` file but don't have a `.gitignore`. I copied it from `.hgignore` but not sure if
> we can remove it as not used. 2. I shamelessly added my IdeJOL plugin to README. There is also mentioned that we can
> create an issue here on GitHub but currently the Issues tab is disabled. The same is for JMH repo. Can you open the
> issues tab? 3. I noted that in `StringCompress` we have a minor bug where in println format pattern we have less
> placeholders than params. While investigated it turned out that it will be better to swap "model" and "hprof file"
> columns for better output. Now it looks like: "total", "String", "String+bool",    "String+oop",  "char[]-2b",
> "char[]-1b", "char[]-1b-comp", "savings(same)", "savings(bool)",
> "savings(oop)",                                                                "model", "hprof file" 3918376,
> 59992,         59992,           59992,            0,           0,               0,           0.000,
> 0.000,           0.000,                     "VM Layout Simulation (X32 model, 8-byte aligned)", "~/empty.hprof"
> 4323184,   119984,        119984,          119984,            0,           0,               0,
> 0.000,           0.000,           0.000,                     "VM Layout Simulation (X64 model, 8-byte aligned)",
> "~/empty.hprof" 4056392,   119984,        119984,          119984,            0,           0,
> 0,           0.000,           0.000,           0.000,   "VM Layout Simulation (X64 model (compressed oops), 8-byte
> aligned)", "~/empty.hprof" 4116336,   119984,        119984,          119984,            0,           0,
> 0,           0.000,           0.000,           0.000,  "VM Layout Simulation (X64 model (compressed oops), 16-byte
> aligned)", "~/empty.hprof"  Also I tried to add a unit test for heap dump analyzer because it currently doesn't have
> any coverage. The test should analyze a heap dump and compare results. But got few problems that want to discuss and
> since there is a closed Issues tab then I'll write it here. First if all I made a heap dump of a "Hello World"
> application on JDK14 and the resulted file even gzipped is more than 900Kb.  I don't want to add such a big file into
> test resources. So here I see two solutions: 1. Create a synthetic heap dump with only few rows. 2. Start a small
> application and get it's thread dump. This wont work because each time we'll get some classes changed. Can you create a
> small heap dump file for a testing?  Another problem I faced when tried to test `StringComprees` with my empty thread
> dump and got an exception `org.openjdk.jol.heap.HeapDumpException: String.value array 34355822528 is not char[] in
> empty.hprof.gz, skipping` This is probably a bug in the JOL itself so I'll attach the
> [empty.hprof.gz](https://github.com/openjdk/jol/files/5346882/empty.hprof.gz) for you to reproduce.

Sergey Ponomarev has refreshed the contents of this pull request, and previous commits have been removed. The
incremental views will show differences compared to the previous content of the PR. The pull request contains one new
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  README.md: Add related projects
  
  Signed-off-by: Sergey Ponomarev <stokito at gmail.com>

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

Changes:
  - all: https://git.openjdk.java.net/jol/pull/7/files
  - new: https://git.openjdk.java.net/jol/pull/7/files/32600701..301a214a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jol&pr=7&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jol&pr=7&range=00-01

  Stats: 5 lines in 1 file changed: 0 ins; 5 del; 0 mod
  Patch: https://git.openjdk.java.net/jol/pull/7.diff
  Fetch: git fetch https://git.openjdk.java.net/jol pull/7/head:pull/7

PR: https://git.openjdk.java.net/jol/pull/7