Debuting gene relations, accessories, and dark mode

This update adds a couple of features that I've been looking forward to implementing for a while.

Complex gene relations

Chickens can now have chicks whose patterns are not the same as their parents. This is based on real-world recessive genes, co-dominance and incomplete dominance! Love me some fun genetics (there's more detailed info at the linked info page).

As part of inaugurating gene relations, we now have three brand new pattern genes that can be obtained only by breeding: double-lace, half-lace, and neck-speckle.

Accessories

Check out Mum's fine new selection of chicken hats and shoes at the Eggschange! The catalogue will be expanded at a later time.

Dark mode

You can toggle dark and light mode by clicking the sun/moon in the top right corner of the page. I'm still ironing out the dark mode presentation of emotes and icons, so those might change over time.