incomplete installations causes warnings which cause ssh mode to fail

[Antoine Martin]

I haven't seen this myself, but this is a definite possibility.
And although one should make sure the installation is complete, that is no excuse for barfing out like this:

2013-04-24 16:05:43,822 connection lost: invalid packet header byte:
  '0x63', not an xpra client? \
  read buffer=0x63616e6e6f74206c6f6164207832363420636f6465633a2063616e6e6...

So we should make sure we don't print warnings to stdout, and maybe also capture the ssh process's stderr and show *that*.

[Antoine Martin]

r3147 should prevent the error above (which was due to a missing picture codec)

[Antoine Martin]

• r3153 also lets the ssh process's stderr come through to make it easier to debug
• r3154 will actually let you see the string rather the hex version of it