Remove new from reserved keywords

This effectively allows stubs to be placed on the `new` method for types.
A strange issue arose when the keyword was allowed.
The compiler failed to resolve the Stub type from the Double initializer.
The error trace goes through null_double_spec.cr.
Running just that spec file confirms the issue is there, but running other individual files doesn't produce the error.
As a workaround, I've put the full path of Stub in the initializer.

spec/issues/github_issue_32_spec.cr

@@ -21,12 +21,9 @@ Spectator.describe "GitHub Issue #32" do
   let(test_instance) { test_class.new }
 
   describe "something else" do
-    # mock TestFoo::TestClass do
+    inject_mock TestFoo::TestClass
-    #   stub self.new
-    #   stub test
-    # end
 
-    xit "must test when new is called", pending: "Mock redesign" do
+    it "must test when new is called" do
       expect(test_class).to receive(:new).with(no_args).and_return(test_instance)
       expect(test_instance).to receive(:test)
       expect(test_class.new).to be(test_instance)

src/spectator/dsl/reserved.cr

@@ -2,6 +2,6 @@ module Spectator
   module DSL
     # Keywords that cannot be used in specs using the DSL.
     # These are either problematic or reserved for internal use.
-    RESERVED_KEYWORDS = %i[initialize finalize class new allocate]
+    RESERVED_KEYWORDS = %i[initialize finalize class allocate]
   end
 end

src/spectator/mocks/double.cr

@@ -74,7 +74,7 @@ module Spectator
     # Creates the double.
     #
     # An initial set of *stubs* can be provided.
-    def initialize(@stubs : Array(Stub) = [] of Stub)
+    def initialize(@stubs : Array(::Spectator::Stub) = [] of ::Spectator::Stub)
     end
 
     # Creates the double.