Rename directory to "planetoid" instead of "src"
Revert "Rename directory to "planetoid" instead of "src""

This reverts commit f8c1d3f85340b5b2539db86ae2f70ccc10b5a6ab.
Reorganize tests.
Revert "Reorganize tests."

This reverts commit 4a8caeff5188c598b476bb6d79ffa7e8d7962fc1.
Remove environmemnent system; it's core now.
Acid lifetime is 10-20 (random).
Also made spitters acid-proof.
Acid monster dies on attack, splurts on death.
Splitters explode in an acidic mess.