Release 1.5.1

• Fixes #36 (closed) :
  b0221ccb is manly a rollback of a parameters property I introduced in 1.5.0 : in fact a simple parameters attribute which is kept in sync with app.GetParameters at the right time (during set_parameters) is a much better option. We may be able to speed that even more with slots.
• 3f59f3d5 is linked to #37 (closed) : just to demonstrate that ABC isn't required since no abstractmethod is defined. I also got some code regarding the mermaid graph I draw in that issue, this is promising ! But will be a big diff (because this is mostly moving functions from App, but a lot of them !)
• Fixes #38 (closed), #39 (closed), #40 (closed)
• Auto env config : add OTB_ROOT/bin in PATH
• May be also #34 (closed) ? This should be easy !
• fixes #43

When merged this should make a significative performance boost for pipelines like test shape (with a lot of app init and accesses to object's parameters).

I'm also going to try pytest (fix #35 (closed)) - mostly for my personal dev knowledge but I believe you'll like those pretty test reports !
Also this will allow us to compute tests coverage.

I originally pushed a branch called develop but this resulted in double pipeline trigger. It was a mess of edits so I removed the branch (!28) .
In 7e462421 I tried to change the yaml to avoid that but it did not change, may be that's in the repo settings (but I don't have access !) or do we need to merge in master for it to be applied ?