Merge branch 'next'

* next:
  Update documentation for the iextags
  Re-wrap the README
  Configure exclusion tags via the cluster tags
  hail: add '-p' option intended for debugging use
  Read cluster tags in the IAllocator backend
  Read cluster tags in the LUXI backend
  Read cluster tags in the RAPI backend
  Introduce support for reading the cluster tags
  Collapse the statistical functions into one
  Specialize the math functions
  Use conflicting primaries count in cluster score
  Node: add function for conflicting primary count
  Add a new node list field
  Add a command-line option to filter exclusion tags
  Introduce tag-based exclusion of primary instances
  Add a tags attribute to instances
  Small change in some list arguments
  Use either \- or \(hy in manpages