removed all dependence on NodeOutputs

If Nodes only have the one output, we don't need to do so much differentiation
between them. Previous iteration used outputs as like a distinct function
within a Node (e.g. length output would return one result, buffer output would
produce a different result - each run different code to produce their results).
Now in this iteration, it's more accurate to say a Node is just one function
(which seems more appropriate for a node system anyway).

app/node/input.cpp

@@ -43,7 +43,7 @@ NodeParam::Type NodeInput::type()
 QString NodeInput::name()
 {
   if (name_.isEmpty()) {
-    return GetDefaultDataTypeName(data_type());
+    return tr("Input");
   }
 
   return NodeParam::name();