Bump to 0.10.0 (#187)

Release version 0.10.0, which includes removing support for
`InstRange::backwards` and support for generating safe points.

Author: elliottt

Cargo.toml

@@ -3,7 +3,7 @@ members = ["regalloc2-tool"]
 
 [package]
 name = "regalloc2"
-version = "0.9.4"
+version = "0.10.0"
 authors = [
     "Chris Fallin <[email protected]>",
     "Mozilla SpiderMonkey Developers",