Mock Turtle Version 3.0.0

** [3.0.0] [14-09-2017]
The realease of a new version has been necessary because I decided to remove
the debug interface from the API. This interface has been problematic, and
its original purpose has been neglected
*** Added
- standard TTY interface to access the soft-CPU serial console output
- minor improvements
*** Removed
- debugfs interface to access the soft-CPU serial console output
- removed library functions to access the debugfs console output
- the ``mockturtle-messages`` tool is not able anymore to access the soft-CPU
  serial console output
*** Fixed
- minor fixes
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