* backported device capability interface
* extended status core with new registers:
  + Vivado version
  + Tapasco version
  + Timestamp (UNIX)
  + Clocks (host, mem, design)
* added new common methods to query the frequencies and globals to set
* used as default by create_subsystem_clocks_and_resets
* extended Platform to contain optional frequencies
* implemented unit tests for each new property
* if set, they are written to Tcl in VivadoComposer