Reorganize removeIJLoops

[SebastienRietteMTO]

Several modifications must be done:

• [x] update the code such as it solves these issues:
  • [x] issue #3
  • [x] issue #4
  • [x] issue #7
• [ ] rename removeIJLoops into removeIJLoopsPHYEX to show that it is specific to PHYEX?
• [x] inline the reDimKlonArrayToScalar in removeIJLoops because it cannot be called without removeIJLoops (and use this part if simplify is True)
• [x] use createExpr for the statement building