Quickstart update

[jpic]

• don't exit on failure because documentation recommends to source this script
• print executed commands
• clarify the state of the script

@njoyard does that work for you ?

[codecov-io]

Current coverage is 91.34% (diff: 100%)

Merging #119 into master will not change coverage

@@             master       #119   diff @@
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  Files            52         52          
  Lines          1052       1052          
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
  Hits            961        961          
  Misses           91         91          
  Partials          0          0          

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