Added QtConcurrent for QtConcurrentRun

This fixes compilation errors on Ubuntu 14.04.1 (required by mainwindow.cpp)
Merge pull request #159 from jweather/autocomplete-test2

Context-aware autocompletion
Added instruction for running under generic linux

JACK doesn't start automatically when running the script. Added instructions for starting it manually. 

Configuring JACK for low-latency performance is not difficult, and there are several guides for how to do this online, but I didn't know a good up to date walk-through to point to. The jackaudio [wiki](https://github.com/jackaudio/jackaudio.github.com/wiki) might be a good choice?
Merge pull request #161 from dcanelhas/patch-2

Added instruction for running under generic linux
Merge pull request #160 from dcanelhas/patch-1

Added QtConcurrent for QtConcurrentRun
Fix location of samples directory within Mac app bundle:

* samples are now correctly autocompleted on the Mac
pull in QHash header