CollInt/ModelicaMixin: Avoid aliasing derivatives
Aliasing of algebraic states to derivative states could result in common
processing/methods failing. For example, when an algebraic state z
is
an alias of a derivative der(x)
, we could no longer ask for
state_at("z")
or state_vector("z")
.
To avoid these issues, this commit uses a new compiler option
allow_derivative_aliases
added in Pymoca 0.8.1. By setting it False,
algebraic states are no longer aliased to derivative states when the
compiler option detect_alias
is set to True.