Fix byte order of checks for literal IPv4 / ehost values

* src/pf/utils.lua: Rename host_uint32 / host_uint16 to uint32 / uint16
  -- the point is to construct a composite uint32 from an ordered sequence
  of bytes; the representation of that number in memory is irrelevant,
  as we have already converted the uint32_t* access to host order.

* src/pf/parse.lua: Fix mask construction for the /len case.

* src/pf/expand.lua: Fix mask construction and adapt to uint32 / uint16
  change.

* doc/host-127.0.0.1.md: Regenerate.