New Global Ids
See #53 (closed)
This implements the following global id system:
- Ids consists of four components: MacroKey, Codim, level, number
- Entities are numbered per codim and level starting at 0
- The number is always between 0 and nEntities[codim] (e.g. 8^level for cubes)
- Entities are sorted first by creatorCodim and secondly by creatorNumber
A specialization for 2d is not yet implemented