Added 'RET'
Added 'JP Z, nn'
Changed rotation instructions to update Z flag
Refactored test for 'RLC A' for reuse with next tests
Added 'RLC B'
Added most of 'RLC R' family of methods
Added 'RLC (HL)'
Changed naming convention of A rotation methods
Added docstring to 'RLC (HL)'
Added 'RLC A'