[0.15.2] add WaitCondition.fluid_count

[Optera]

WaitCondition doesn't list any type for the new fluid conditions.
Either the page isn't updated of the fluid count condition is not exposed through the api.

[Rseding91]

The docs page is outdated. Which happens frequently because it's not linked to the code in anyway... a general problem.

I've updated it for the next version of 0.15. However if you want to use them now the names are "fluid_count", and "robots_inactive" for the 2 types it doesn't list.

[Optera]

Thanks for the update.