🦑 Excise time

[thorstenhater]

Excises time from NMODL as per our policies not to let users peek behind the curtain.

Closes #1252

[thorstenhater]

bors try

[bors]

try

Build failed:

• ci/gitlab/gitlab.com

[thorstenhater]

@bcumming the runner is having another bad hair day.

[boeschf]

This will potentially break some code where users rely on this feature. What's the our policy with respect to deprecation warnings/breaking changes?

[thorstenhater]

That we are in 0.x.y land and will politely inform our users ;) Time has been in NMODL mainly for implementing I_Clamps, which we do differently now. None of our internal catalogues uses it.

In general we try to minimise our ABI surface and try to keep our users away from the soft underbelly of Arbor.
Using time someone could try to implement their own solvers/integrator, which we decidedly do not like.
If desparately needed, adding a trivial ODE (t' = 1) restores it, but makes our dislike obvious.
This also saves an array in shared state, (plus one on the GPU, if present).