run-tests: move env into Test Environment variables are an implementation detail of how tests are executed. This patch moves environment variable logic into Test and completely hides it from the outside. With this patch, a Test can be executed with two lines: init + run(). Tests are still single-use and take a more arguments to the constructor than likely necessary. These will get addressed in subsequent patches.

run-tests: move killdaemons into Test.run() killdaemons() was the only part of runone() looking at env variables. We move killdaemons() into Test.run() to enable us to fully move env into Test.

run-tests: move replacements and port management into Test replacements and ports are really implementation details of a Test. They have been moved to instance variables.