GBWTGraph v0.4

• CachedGBWTGraph: A GBWTGraph overlay that uses the cached interface automatically. Intended for algorithms that repeatedly access the edges in a small subgraph.
• Minimizer index v7 (compatible with v6):
  • An option to use bounded syncmers instead of minimizers.
• Graph algorithms in algorithms.h:
  • topological_order(): Find a topological order for all handles in the subgraph induced by a subset of nodes.
• New queries:
  • GBWTGraph::cached_follow_edges(): A version of follow_edges() using CachedGBWT.
  • hits_in_subgraph(): Report minimizer hits in a subgraph induced by a set of nodes.
• Changes to path cover:
  • local_haplotypes(): Revert to the path cover algorithm if there are no haplotypes in the component.
  • augment_gbwt(): Augment an existing GBWT with a path cover of missing components.