Change module to object in error messages

We talk about objects, not modules, in the documentation, so error
messages should align with that.

Author: odersky

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -1465,7 +1465,7 @@ object SymDenotations {
       else if myFlags.is(Trait)  then "trait"
       else if isClass            then "class"
       else if isType             then "type"
-      else if myFlags.is(Module) then "module"
+      else if myFlags.is(Module) then "object"
       else if myFlags.is(Method) then "method"
       else                            "val"
 

compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala

@@ -419,8 +419,8 @@ class PlainPrinter(_ctx: Context) extends Printer {
       if (sym.isClass) "package object class"
       else "package object"
     else if (sym.isAnonymousClass) "anonymous class"
-    else if (flags.is(ModuleClass)) "module class"
-    else if (flags.is(ModuleVal)) "module"
+    else if (flags.is(ModuleClass)) "object class"
+    else if (flags.is(ModuleVal)) "object"
     else if (flags.is(Trait)) "trait"
     else if (sym.isClass) "class"
     else if (sym.isType) "type"