v0.3.1: Major gameplay changes

Hello again! After collecting the first bits of feedback from v0.3.0, I've made a few big changes that I wanted to announce here.

To give career mode a clearer and more challenging goal, I've made Biomarks more important, in a few ways. Now, cultures will have an ongoing maintenance cost, which scales with culture size. This means that there is no longer an infinite money loop where your cultures can just explode in population without consequence. You'll have to think more about population scaling and make pruning decisions in order to maintain your culture. Other actions will also cost Biomarks, such as harvesting your cells. I might have to buff cell values to compensate, but this should make Biomarks and carefully curated collections feel like something actually meaningful rather than just "number go higher".

I also want to emphasize agency by making the placer tools more of a focus. I've added the ability to place crystal directly into a large culture. These change their surrounding environment, so you can now set up distinct zones more easily. I've also fixed up the particle placer and will be adding more particle types like specific toxins for population and contamination control and mutagens for accelerating and guiding mutations.

To add more challenge, I have incorporated bacteria and larger non-player cells into a contamination system. Cultures will become contaminated with competing cells, and you'll be able to use the placer tools to try to fight them (or pay a Biomark maintenance premium to sterilize your culture).

I also fixed a major bug blocking plasmodial growth, along with the other usual bug fixes and balance tweaks.

These are all WIP, and I will be continuing to release daily updates as things move along. I figure it is better to release rough in-progress builds more often than to go quiet while I try to perfect everything.

Thanks again for playtesting!!!! Your feedback has been incredibly helpful.Changelog:
v0.3.1:

* Major gameplay changes aimed at reinforcing game loops:

- Added more HUD readouts for gameplay stats

- Added contamination to cultures from bacteria and non-player cells

- Added ongoing maintenance costs for cultures that scales with cell count, in addition to other costs so that Biomarks are more important

- Improved particle placer and added direct crystal placement, with associated Biomark costs

* Balance adjustments:

- Early cells can undergo mitosis sooner

- Viruses are more common

* Various tutorial improvements

* More HUD improvements

* Fixed bug blocking plasmodia growth

* Fixed performance regressions