Add configuration to use hie-wrapper to launch hie (default: false)

[Tehnix]

Following up on haskell/haskell-ide-engine#439.

This adds a hie-wrapper.sh script, which tries to automatically select a hie version that matches the GHC version of the project.

It is enabled by a configuration flag, useHieWrapper, which is set to false by default, until we know if it is stable enough to enable by default. It assumes that the user has built different versions of hie and postfixing them with the GHC their are built for (falling back to plain hie). I've added a Makefile to make this easy in haskell/haskell-ide-engine#447.

I'm amenable to any changes to the script etc, just let me know if there's something you would prefer instead!

Also, I set debug=1 for now, so one can tail -f /tmp/hie-wrapper.log to see if it works. It'll look something like,

Launching HIE for project located at /Users/tehnix/GitHub/Tehnix/STM-Fun
  Using stack GHC version
  The Glorious Glasgow Haskell Compilation System, version 8.0.2
  Project is using GHC 8.0.2
  hie-8.0.2 was found on path
  Starting HIE

[Tehnix]

Also, if anyone can help port this to batch, that'd be swell :) I've neither Windows to test on, nor any real experience with batch, unfortunately.

[alanz]

Why are the tests taking so long?

[Tehnix]

Hmm, it seems to have passed Linux tests, but is waiting on macOS. I heard from others lately that they had been super slow, but not exactly sure why though (the builds haven't even started there) :/

[alanz]

Ok, I am going to merge, its unlikely to affect things.

[alanz]

It's live on the market. Thanks.