Note that the d_zoom_* vars are kept as double to avoid error build-up
when changing them a lot from the UI.
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
It's split into:
- A generic "base" sink that handles pretty much everything except
managing a GL context and getting the UI interaction for it
- The GLFW specific part
This is preparation for for WX and QT widget implementations of a
fosphor sink.
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>