* tapasco::ip contains methods to instantiate common IP
* common/ip.tcl automatically generates methods based on the stdcomps
  directory: every name has its own instantiation method called
  create_<name>, which takes only a name as an argument
* specialized constructors go into common_ip.tcl and can override the
  auto-generated ones
* removed all createXY procs in common.tcl and fixed all dependent
  scripts accordingly
* removed ill-fated "clocks_and_resets" bundle - sad, but didn't work
  correctly in Vivado