Updated after June workshop

The Air vehicle level Functional Hazard Analysis  (AFHA) identifies the Failure Conditions (FCs), their effects, and the severity classes of these effects. 
It is an input of many activities pertaining to the safety assessment process. In particular, it is requested for performing the Preliminary  Air vehicle level Safety Assessment (PASA).
The Failure Conditions are also requested when evaluating satisfiability of the Overarching Properties

create directories for each layer of the development assurance process

Updated based on meeting discussion,  Anne-Perrine and Alexandre comments

This reverts commit 13d59d12.

This reverts commit 7e0b5486.

First draft of the specification at AV level (step 1)

- 1st sheet : remarks
- 2nd sheet :  interfaces issues

document with remarks on specification documents
- 1 sheet on document "OP oriented"
- 1 continuing remarks on last version
- 1 sheet with analysis of interfaces : inconcistencies and missing
elements

This reverts commit b5bcb8fa80ac69a350455f930cf5f57397829812.

system modelization  with verification of interfaces

in particular "e.g " into e.g. " and "i.e " into "i.e. "