- construct container depending on type and bits depth
- use shared pointer for ImageCurves, gives easy operator=
- const'ify all accessor methods
- fix </<= issues: array has size NUM_POINTS, index must be checked for "<"
- addMethods to get a CurvesContainer and to set the curves from a container
- setCurvePoints can also except polygons of differing size,
  simply disabling missing points. May be it doesnt work in CurvesWidget,
  but it's not used from there
- add a method isLinear to test if a channel curve is linear
- add methods to store and read from a simple binary representation


svn path=/branches/extragear/graphics/digikam/; revision=1195874