- Aligned the vertex/edge descriptor types to allow:
  - Proper implicit conversion from non-const to const variant
  - Comparison between a const and non-const variants
- Refactored the `graph` class and the internal implementation types to define and utilize const and non-const element descriptors based on the graph's constness
- Relaxed the `c_graph` concept to allow multiple value/type categories of the `graph` class
- Introduced helper typedefs to easily extract the typedefs from a graph type in generic contexts
- Refactored the internal specialized implementation types to use the explicit object parameter feature in order to be used as mixin base types instead of simple static method dispatchers
- Aligned the algorithm implementations to work with the new, aligned graph implementation

- Aligned the hyperedge descriptor type to allow:
  - Proper implicit conversion from non-const to const variant
  - Comparison between a const and non-const variants
- Refactored the `hypergraph` class to define and utilize const and non-const element descriptors based on the hypergraph's constness
- Relaxed the `c_hypergraph` concept to allow various value/type categories of the `hypergraph` class
- Introduced helper typedefs to easily extract the typedefs from a hypergraph type in generic contexts
- Aligned the algorithm implementations to work with the new, aligned graph implementation
- Additional cleanup of the GL module