ComparableXD and Bentley-Ottmann

Based on #344, will be squashed after #344 is merged.

What it does:
* Intro AbstractSorter::insert_sorted to insert an element in an already sorted array using a binary search.
* Intro the Comparator2D and Comparator3D classes
  * Will also be used as points in mnit/paninit::Display, and to implement QuadTree
  * Is a parameter type for each axis too much? One may use different types for a 2d games with layering... or to classify data.
* Intro Bentley-Ottmann for Int only
* Adapt Bentley-Ottmann to use Numbers and thus compatible with Floats too
    * This will be squashed before merge if accepted