v0.28.0

Added

• Add source- and destination-clock-domain "halves" for the clock domain crossing (CDC):
  axi_cdc_src and axi_cdc_dst. This is implemented by refactoring the axi_cdc module, so the
  implementation is reused from the existing axi_cdc module. To avoid code duplication, axi_cdc
  now instantiates an axi_cdc_src connected to an axi_cdc_dst.

Changed

• axi_lite_to_apb: Make pipeline registers on request and response path optional (can be enabled
  with the new PipelineRequest and PipelineResponse parameters), and disable those pipeline
  registers by default.

Fixed

• axi_demux: Improve compatibility with new version of QuestaSim's optimizer (vopt) (#169).
  Before this workaround, QuestaSim 2020.2 and 2021.1 could segfault on instances of axi_demux.