git subrepo clone git@github.com:ingydotnet/swim-pgx ext/swim-pgx

{"local":
  {"subdir":  "ext/swim-pgx"
  ,"action":  "clone"}
,"remote":
  {"url":     "git@github.com:ingydotnet/swim-pgx"
  ,"branch":  "master"
  ,"commit":  "b988b25"}
,"git-subrepo":
  {"version": "0.1.0"
  ,"commit":  "d1a9fbd"
  ,"origin":  "git@github.com:ingydotnet/git-subrepo"}}
Symlink grammar into share/ dir