No constant folding done for first arg of qp()

### Expected Behaviour
It should be OK to have the following in a Chronikis program:

qp(24.0 * 7.0, 0.5, 10, rho_w, sigmap_w)

### Actual Behaviour

I get the following error:

chronikisc: toModelBody requires an argument in BasicModel form
CallStack (from HasCallStack):
error, called at src/InferShapesBoundsImpl.hs:205:17 in compiler-0.2.0.0-9V7qdTqRCYd5vzfi3sufpJ:InferShapesBoundsImpl

If I run with the `-x` flag, I find that the call to `qp()` doesn't get expanded.

Start at the error reported in src/InferShapesBoundsImpl.hs:205 and trace how qp() is handled when its first argument is the constant expression 24.0 * 7.0. Use the -x flag to inspect expansion; done means the expression is accepted and the qp() call is expanded without the toModelBody error.

Written by the indexing model from the issue text.