Revises how Topic and NanoUI shares allowance-logic.

All mob-interaction logic now resides in nanointeraction.dm and is called by the base CanUseTopic().
Specifics for when objects allows mob-interaction can be specified by overriding CanUseTopic(), see machinery.dm.

nano/js/nano_base_helpers.js

@@ -48,6 +48,10 @@ NanoBaseHelpers = function ()
 			round: function(number) {
 				return Math.round(number);
 			},
+			// Returns the number fixed to 1 decimal
+			fixed: function(number) {
+				return Math.round(number * 10) / 10;
+			},
 			// Round a number down to integer
 			floor: function(number) {
 				return Math.floor(number);