IGV can jump to JMH sources & more

[JaroslavTulach]

Pull Request Description

Improvements to behavior and visual appearance of IGV Enso integration.

Checklist

Please include the following checklist in your PR:

• The documentation has been updated if necessary.
• All code conforms to the
  Java,
  style guides.
• All code has been tested:
  • Unit tests have been written where possible.

[JaroslavTulach]

Steps to use IGV properly:

• sbt buildEngineDistribution
• sbt benchOnly StringBenchmarks
• download latest version of enso4igv module
• Use File/Open Project... menu item to open enso/engine/runtime directory
• Use Window/Projects to open the "projects view"
• Navigate to a benchmark file
• Ctrl+Click on any JMH file (like RunResult) - sources of the right class are going to be opened