environments, error messages, and stack traces, oh my!

Changed the way processes are launched.
multishell.openTab and kernel.run now accept the current environment as a parameter.
That new process inherits a copy of the passed environment.
Reduces complexity as the calling process is not required to create a suitable env.
Stack traces have been greatly improved and now include the stack for coroutines that error.

sys/autorun/log.lua

@@ -39,7 +39,7 @@ local function systemLog()
 	keyboard.removeHotkey('control-d')
 end
 
-kernel.run({
+kernel.run(_ENV, {
 	title = 'System Log',
 	fn = systemLog,
 	noTerminate = true,