## FbTk/ImageControl.hh:
* moved 'getSqrt()' over to TextureRender.cc because it is used only there
* removed unused members m_root_window
* use std::vector<> for colors and for the gradient buffers.
## FbTk/ImageControl.cc:
* fixed memory leak in '~ImageControl', 'pixels' where not deleted[]
at all. switched to std::vector, non-issue anymore.
* moved identical code into functions 'allocateUnallocatedColors', 'initColortables'
## FbTk/TextureRenderer:
* removed 'from', 'to', 'interlaced' from class, only used in
'renderGradient()' and are actually part of the given
texture.
* removed 'xtable', 'ytable' from class, only used in
'renderGradient()'
* removed 'colors' from the class, is part of 'control'
* moved render actions (invert, bevel1, bevel2, *gradient), they need more
love but for now this is sufficient
