Added more colorschemes and a new GUI to create more colorschemes.

- Added support to colorschemes from OsiriX.
- Created a new GUI to create colorschemes
  - This GUI generates the event EVT_CLUT_NODE_CHANGED when the user
    changes the position and colours of the nodes.
  - This GUI has style setted to FRAME_FLOAT_ON_PARENT, to make this GUI
    stay always on top of invesalius GUI.
- Added pubsub event "Update window level text" to change WW&WL text