docs/SETUP: Improve the init section for virtualenvwrapper.
docs/SETUP: Improve the init section for virtualenvwrapper.

  - reorganize the steps to be more comprehensible
  - make sure the commands examples work fine

stfp/memopol2,stfp/memopol2,stfp/memopol2,yohanboniface/memopol-core,yohanboniface/memopol-core,yohanboniface/memopol-core