Missing check for data range match when loading transfer function

[codeling]

When loading a previously stored transfer function, no check is performed whether the range of the loaded transfer function matches the range of the current dataset. That can lead to the TF not covering the whole range, or to it covering more than the datasets data range.

Two options:

• Prevent loading TF if its range does not fit data range.
• (preferred) Adapt loaded TF to match data range, and inform user about adaptations that were performed, for example in the log.

[codeling]

Fixed with https://github.com/3dct/open_iA/commit/2760e6564f21c03b7c9cab3b4328720c746e6373; an error is issued if there is a range mismatch, and the transfer function is adapted so that it covers the whole data range (keeping those points of the loaded TF that fall within the valid range).