fix-delete-all: Use OFPG_ANY when deleting all flows to select all flows regardless of their group. This fixes an error message that was reported when deleting all flows on OVS.
print-error: Print error type and code.
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Merge branch 'fd-leak' of https://github.com/frenetic-lang/ocaml-openflow into fd-leak

Conflicts:
	async/Async_Highlevel.ml
leak
max_pending_connections is the key.