node-v1.2.9

Runs against any current panel (still protocol version 4). Needed for PROXY
protocol, which panel 1.2.15+ refuses to turn on for a group until every node
in it runs this release; nodes that do not use it lose nothing by waiting.

Added

• PROXY protocol (v1 and v2), per rule, TCP only (panel 1.2.15+). With
  "send" on, the node writes the header to the target before any client
  byte: the real client and the address it dialled. With "accept" on, the
  node reads a header (v1 or v2, assembled across reads, at most 5 s) from
  the start of each inbound connection, from a trusted source when sources
  are set, takes the client from it, and forwards only what follows; a
  connection without a valid header is closed and never reaches the target.
  Client bytes that arrived with the header are forwarded first and billed
  as usual; the header itself is not billed. Mixed address families go out
  as IPv6 with the IPv4 side mapped. Changing the setting restarts the
  rule's listener without dropping live connections.