refactor pressure logic toggle to act as option enum

default_settings.lua

@@ -29,16 +29,22 @@ local settings = {
 	delete_item_on_clearobject = true,
 }
 
+pipeworks.toggles = {}
 -- documentation for toggles controlling pressure logic features.
 -- do not edit this file directly;
 -- instead, create pipeworks_settings.txt in your world directory,
--- and copy the uncommented lines from the block comment below into it.
+-- and copy the uncommented lines from the block comments below into it.
+--[[
+-- flow logic implementation.
+-- set to one of the following strings.
+-- "classic": classic mode written by VanessaE
+-- "pressure": pressure metadata based, written by thetaepsilon.
+--	has caveats such as water speed issues though.
+-- setting to nil inhibits all flow logic, useful for debugging ABM crashes,
+-- or for rendering the pipes purely decorative.
+]]
+pipeworks.toggles.pipe_mode = "classic"
 --[[
--- enable pressure logic mode instead of "classic" mode.
--- WARNING: this changes a few things, most noticeably how pumps work.
--- you'll want to make sure they're fed by an infinite spring.
-pipeworks.toggles.pressure_logic = true
-
 -- force-enable finite water handling mode.
 -- this changes the way that water node placement is handled;
 -- volume will always be preserved,