Various new PSL assertions to check ports during Wishbone write & read
transfer and reset state

New testcases for checking correctness of removing and overwriting
entries in dictionary. Furthermore the hasKey() method is tested and
the clearing of the dictionary with the clear() method

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

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 :)