A new packae DictP.vhd is added which contains a simple implementation
of a dictionary type. It consists of a protected type t_dict which
contains procedures & functions which serve as methods to interact with
the protected type. The t_dict type is realised by a (double)
linked-list using access types.
The key type is string of arbitrary size, the data type is
std_logic_vector of arbitrary size. The t_dict type provides following
interface methods:

  * set: set a key/value pair
  * get: get a key/value pair
  * del: remove a key/value pair
  * init: initialise the dictionary
  * clear: remove all key/value pairs
  * hasKey: check if a key exists in the dictionary
  * size: get number of key/value pairs

By using an actual version of GHDL, we don't need the VHDL-08
proposal libraries anymore. Enough features of VHDL-08 are integrated
in GHDL to compile OSVVM and our testbenches

The new common folder holds packages and designs, which can be used
either for synthesis & simulation. The first file is UtilP.vhd, a
package containing vatious helper functions:

  * and_reduce(): function to and'ring all items of a vector, overloaded
                  for std_logic_vector & boolean_vector
  * or_reduce(): function to or'ring all items of a vector, overloaded
                 for std_logic_vector & boolean_vector
  * even_parity(): calculate the even parity of a std_logic_vector
  * odd_parity(): calculate the odd parity of a std_logic_vector

By using an std_logic_vector access type for the data field in the
queue record, we cann now push data with any arbitrary length in the
t_queue object. Mixed lengths are also possible now :)