remove io overrides

they were causing side effects when writing luacov reports

library/lua/dfhack.lua

@@ -51,26 +51,6 @@ if dfhack.is_core_context then
     SC_UNPAUSED = 8
 end
 
--- redirect any output explicitly sent to io.stdout or io.stderr to the standard
--- output sinks. note that although the functions take and pass ...,
--- only the first string argument will be printed by dfhack.printerr().
-if not io_write_rerouted then
-    local io_file_methods = getmetatable(io.stderr).__index
-    local std_io_file_write = io_file_methods.write
-    io_file_methods.write = function(f, ...)
-            if f == io.stdout then
-                print(...)
-                return f
-            end
-            if f == io.stderr then
-                dfhack.printerr(...)
-                return f
-            end
-            return std_io_file_write(f, ...)
-        end
-    io_write_rerouted = true
-end
-
 -- Error handling
 
 safecall = dfhack.safecall