old servers error out with 0.11.x clients

[Antoine Martin]

The problem comes from the newer bencoders, which do not send dictionary keys in a specific order (pointless since python will immediately stick them in a dict which loses the order), solutions:

• restore dict order (yuk)
• apply patch attached to old branches (which will not be applied by distros since they're stuck on broken versions...)

The error shows up in the server log as:

Traceback (most recent call last):
  File "/usr/lib64/python2.7/site-packages/xpra/protocol.py", line 575, in do_read_parse_thread_loop
  File "/usr/lib64/python2.7/site-packages/xpra/bencode.py", line 72, in bdecode
  File "/usr/lib64/python2.7/site-packages/xpra/bencode.py", line 45, in decode_list
  File "/usr/lib64/python2.7/site-packages/xpra/bencode.py", line 55, in decode_dict
ValueError
connection lost: gibberish received: 'l5:hellod16:...

[Antoine Martin]

this fixes the old servers

[Antoine Martin]

r5236 restores compatibility with old servers, backport for v0.11.x branch in r5239

Note: if you've come here because you are seeing this error, this means you are using an old, buggy and unsupported server...

[migration script]

this ticket has been moved to: ​https://github.com/Xpra-org/xpra/issues/499