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

Added (but not integrated) the clut_imagedata widget

Remove unused imports from clut_imagedata

The ClutImagedata is changing the slice lookuptable

Showing the histogram at the clut widget

Using checkbox instead of radiobutton to color menu

Applying ww & wl changes to the color table generated by clut_imagedata

Window&level affects clut colors

Window&level affects clut colors

Removed non-color presets from color preset dir

Hidding clutimagedatadialog when user selects another color preset

Removed idiot print

Keeping nodes after closing clutimagedata

Not passing ww&wl to clutimagedata anymore

Generating EVT_CLUT_POINT_MOVE when the clutimagedata is shown

Since EVT_SHOW binded to a wx.Panel is not working with 2.8, I'm binding
the OnShow method to EVT_IDLE and unbinding after the first time this
event is generated.

Using keyboard left and right to change nodes

Enter give the user option to change node colour

(shift +) Tab selects the next (previous) node

Improvements on the drawing of clut_imagedata

ClutImagedataDialog is dealing with clut_imagedata events

Added properties in clut_imagedata to get the ww&wl

Added a pubsub method to update the ww&wl text

WW&WL interactor style affects clut_imagedata widget

Style: the position of window_level and window_width

Delete key deletes a node

Cleaning and closing clut_imagedata dialog when a project is closed

Refreshing clut_imagedata after user change node color

Clut_imagedata dialog setted style to STAY_ON_TOP

Change clut_imagedata dialog style from wx.STAY_ON_TOP to wx.FRAME_FLOAT_ON_PARENT

Cleaning code related to clut_imagedata dialog in viewer_slice

Cleaning code related to clut_imagedata dialog in viewer_slice

EVT_CLUT_POINT_MOVE renamed to EVT_CLUT_NODE_CHANGED

Generating event when user selects custom color scheme

Removed OnShow method from clut_imagedata

Remove useless prints

Reseting things when closing a project