Trim trailing content when obtaining dedicated_server_step

This change trims anything starting with the first space from dedicated_server_step, including single-line comments following the configured value specifically, before using it for calculations. It fixes compatibility-breaking crashes with some mods/games, which change the mentioned value by adding a comment after it. Such a comment is, as far as I know, syntactically valid, and is accepted by the engine it seems.

worldedit/manipulations.lua

@@ -101,7 +101,7 @@ end
 local function deferred_execution(next_one, finished)
 	-- Allocate 100% of server step for execution (might lag a little)
 	local allocated_usecs =
-		tonumber(minetest.settings:get("dedicated_server_step")) * 1000000
+		tonumber(minetest.settings:get("dedicated_server_step"):split(" ")[1]) * 1000000
 	local function f()
 		local deadline = minetest.get_us_time() + allocated_usecs
 		repeat