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/hotkeys.lua

@@ -10,9 +10,8 @@ if multishell and multishell.getTabs then
 		local tab = kernel.getFocused()
 		if tab and not tab.noTerminate then
 			multishell.terminate(tab.uid)
-			multishell.openTab({
+			multishell.openTab(tab.env, {
 				path = tab.path,
-				env = tab.env,
 				args = tab.args,
 				focused = true,
 			})