Code:
  * Test mutant with dynamically created zombie.

Mutations:
  * Add true masgn mutations
  * Add some kind of a "do not touch me object" that raises on all messages.
    It can be used to make sure each literal value is touched.
  * Replace nil or add "do not touch me object" to literal mutations.
  * Mutate options on Regexp literals
  * Add mutations for dynamic regexp symbol and string literals
  * Add timeout to terminate infinite loops

Loader:
  * Make sure loader does not change visibility of injected mutants

Matcher:
  * Allow matches on attr_reader with literal name argument(s)?
  * Allow matches on define_method with literal name argument?

jruby-support:
  * Create a runtime per mutation to kill mutations in isolation