Add a branch for OpenSim 0.9. 🔼

Call it SledjChisel.

reported=2019-05-19 06:58:14

reporter=onefang

priority=immediate

category=TODO

severity=block

resolution=fixed

2019-05-19 13:27:15 onefang: The 0.9 stuff is in the new SledjChisel branch, including the work to date.

2019-05-21 10:31:56 onefang: The SledjChisel branch got renamed to SledjChisl, coz it matches the style.