Move to Wx3.0

The current state is something between wxWidgets 2.9.3 and wxWidgets 3.0.
This pull request will update wxWidgets to version 3.0 and solve some Linux errors thanks to wx developers help:
http://trac.wxwidgets.org/ticket/15529
Also now system wxWidgets 3.0 will be used by default.

Please close issues: #352 #449 #653