Remove useless print statement from wxHMI GUI code

It's py3k incompatible.

Rename extension instance 'wxHMI' to 'wxglade_hmi'

It is necessary because of following commit 7f59aa398669 ('WxGlade HMI extension now does
only instanciate wx object who's name match extension's name. If no
object match the name and no code is provided in 'start' user python
code section, then a warning is issued')

Remove backup .bak files

Drop EtherCAT examples, because they are non-functional without releasing motion control library

Closes #38