Fuse.Scripting: lift ExecutionThread out of ScriptMethod
Fuse.Scripting: lift ExecutionThread out of ScriptMethod

This allows us to fix up ScriptMethod<T> initialization so we no
longer need a dummy-constructor to avoid repetition. Also,
ScriptMethodInline no longer needs to pretend to care.

nekronos/fuselibs-public,fusetools/fuselibs-public,kusma/fuselibs-public,kusma/fuselibs-public,yupferris/fuselibs-public,nekronos/fuselibs-public,eksperts/fuselibs-public,fusetools/fuselibs-public,nekronos/fuselibs-public,fusetools/fuselibs-public,nekronos/fuselibs-public,fusetools/fuselibs-public,eksperts/fuselibs-public,fusetools/fuselibs-public,kusma/fuselibs-public,nekronos/fuselibs-public,cbaggers/fuselibs-public,eksperts/fuselibs-public,cbaggers/fuselibs-public,cbaggers/fuselibs-public,eksperts/fuselibs-public,fusetools/fuselibs-public,fusetools/fuselibs-public,yupferris/fuselibs-public,nekronos/fuselibs-public,kusma/fuselibs-public,nekronos/fuselibs-public,eksperts/fuselibs-public,yupferris/fuselibs-public,eksperts/fuselibs-public,cbaggers/fuselibs-public,cbaggers/fuselibs-public,yupferris/fuselibs-public,kusma/fuselibs-public,yupferris/fuselibs-public,yupferris/fuselibs-public,kusma/fuselibs-public,yupferris/fuselibs-public,cbaggers/fuselibs-public,cbaggers/fuselibs-public,kusma/fuselibs-public,eksperts/fuselibs-public