Added a jsbsim compilation fix without updating jsbsim.
[darwin] remove to_string() only on clang >=5
[darwin] Updated ivy-python url
[darwin] Improved binary installer env setup
[darwin] Binary build script - fix git repo url
[darwin] Add pygame as pprz-tools dependency
[darwin] binary env set script syntax fix
[darwin] binary build script - fix escaped var bug
[Darwin jsbsim] Backported pkgconfig patches from debian.
Merge pull request #42 from esden/jsbsim_pkgconfig

[Darwin jsbsim] Backported pkgconfig patches from debian.