* Implemented ButtonGroupManager.
  It is responsible for positioning of buttons, any animations
  during switching, etc.
* Added MaterialButtonLookAndFeel class which implements
  flat button look and feel following Google Material Design Guidelines.

Created Xcode projects for all currently-built plugins.  Added Xcode workspace with "All" scheme for building GUI and all plugins.  Addressed some compiler warnings in plugin code.

On OS X, copy Rhythm-related files to the application bundle's Resources folder, and use the bundled copies at run time

- Sync signal, wired to BNC out with the update rhd2000.bit, can be set
  to a multiple of the sample clk period using the RHD2000Editor
- This commit corresponds to this pull request:
  https://github.com/open-ephys/rhythm/pull/11

removed manual loading of all plugins, clearingout compile issues with string manipulations, adding makefile to arduiono, testsing loading