i2psnark: Disable streaming pings (ticket #1142)

  - Fix ConnectionAcceptor not restarting after tunnel
    restart, preventing incoming connections
  - locking tweaks
  - cleaner reschedule tweaks
  - don't store server socket locally
  - constructor tweaks / finals
  - Stop acceptor when tunnel disconnects
  - javadocs

I2PTunnel: Don't send 'X-Forwarded-For' on HTTP server tunnels for anonymity reasons (reported by 'trixie' on IRC).

          (thx str4d)

not restarting correctly, caused by previous checkin

  a client socket manager configured with i2cp.newDestOnResume,
  or a shared client.
  This prevents lots of orphaned StreamingTimer threads.
  There are still cases where these threads may stick around,
  when a tunnel is stopped but not restarted. We don't know in
  some cases when a tunnel could be restarted and when it can't.
  destroySocketManager() should always be called when discarding a
  SocketManager but i2ptunnel doesn't do that now. More to do,
  but this fixes the most common case of leaked threads.
  Related tickets: ##642 #961

can be private and the lookup for the form is more efficient.

-28

  - Add support for country variants (ticket #1133)
  - Refactor data in ConfigUIHelper
Config files: Allow empty values

 - volatile -> atomic
 - unused code and fields
 - closing streams
 - hashCode / equals
 - known non-null
 - Number.valueOf
 - new String
 Still avoiding SAM, BOB, SusiMail