= Improvements

* The r.is optimization added in 3.46.0 has been extended to optimize
  all single argument calls. This results in the following speedups
  based on argument type:

  * Hash/Class matching: 20%
  * Symbol matching: 25%
  * Array matching: 35%
  * Proc matching: 50%
  * false/nil matching: 65%

* Roda now uses defined?(yield) instead of block_given? internally
  for better performance on CRuby.  defined?(yield) is faster as it is
  built into the VM, while block_given? is a regular method and has
  the overhead of calling a regular method.  Note that defined?(yield)
  is not implemented correctly on JRuby before 9.0.0.0, so this
  release of Roda drops support for JRuby versions before 9.0.0.0.
