OSX: Added new generic progress bar (including indeterminate status).

- Added BasicPath, BasicPathLine and IBasicPathItem to define generic
paths. More implementations of IBasicPathItem will be added as needed.
- Added DrawPath to IGraphicsContextWrapper and implemented on OSX.
- Added path conversion to GenericControlHelper on OSX.
- Added ProgressBarControl, which is a flat progress bar with also an
indeterminate status with a nice animation.
- Added CircularProgressBarControl, but it is empty for now.
- Replaced progress indicators by new generic progress bars throughout
the app.