Ice rings

• Please see Wishlist#Would be nice to have: there's a list of additional (high-) resolution ranges one might want to exclude (in CORRECT).
• A currently possible way to prevent ice rings from spoiling the IDXREF step is to set TRUSTED_REGION=0 <some small value> for INIT, where <some small value> is calculated such that ice rings are excluded.
  Drawbacks: a) <some small value> needs to be calculated by Bragg's law (the formula [math]\displaystyle{ \frac{Wavelength \cdot Distance} {2 \cdot NX \cdot QX} }[/math] should give approx. 4 Å cutoff). b) after successful indexing, INIT needs to be re-run.
• Please see Optimization for how to treat remaining ice reflections showing up as "Aliens" in CORRECT.LP.