* postBuildActions can no longer use the Module instance directly, since
  Chisel3 prohibits its instantiation outside of a Driver
* added a configuration object of type Any instead, which will be passed
  to the postBuildActions - we do not actually need the Module instance,
  only the configuration options passed to it
* Chisel3 no longer supports renaming of top-level ports (setName has
  vanished); auto-inference of the AXI-interfaces is not possible
  without renaming
* fixed by adding interface definitions to CoreDefinition:
* each module may declare "known" interfaces; in this case the IP-XACT
  Tcl will match to the generated port names manually

* args can contain names of modules, only those are built
* names are case-insensitive
* no args builds all modules
* added uniqueness check for module names

* ModuleBuilder generalizes the building of modules:
  user needs only supply list of CoreDefinitions to build
* provides main() to run automatically
* CoreDefinition: additional constructor to automatically
  supply root dir in ip/<name> subdir

* Scala model for core definitions
* support for reading and writing Json format

* based on Python, Vivado IP Integrator
* produces component.xml with correct reset polarity