At the request of OMEGAcrab992 in Discord I've reenabled contaminants as an optional setting in the lab bench and creative lab, and some bionet nodes will have no rival lab AI and just contaminant cells.

There are also some other bug fixes:

v0.4.5a-6:

* Re-enabled contaminants. Available as optional new culture settings from the lab bench/creative lab

* Lab bench no longer shows bionet cultures in the CULTURE list

* Lab bench cultures exit to the lab bench

* Placing cells via seed is refused when the placement area isn't suitable

* Newly placed cells have a 0.25s survival grace period

* Splice correctly spends specimens from the cryobank

* Preview cells that die on spawn are respawned automatically

* UI fixes