Add mutation for /a*/ -> /a/

lib/mutant/mutator/node/regexp/greedy_zero_or_more.rb

@@ -16,6 +16,7 @@ module Mutant
           def dispatch
             emit(s(:regexp_greedy_one_or_more, *children))
             emit_subject_mutations
+            emit(subject)
           end
         end # GreedyZeroOrMore
       end # Regexp

meta/regexp/regexp_greedy_zero_or_more.rb

@@ -4,6 +4,7 @@ Mutant::Meta::Example.add :regexp_greedy_zero_or_more do
   singleton_mutations
   regexp_mutations
 
+  mutation '/\d/'
   mutation '/\d+/'
   mutation '/\D*/'
 end