`pwnlib.tubes.tube.clean_and_log()` is now a no-op if the tube is not connected
Made call to the constructors of the listeners non-blocking
Added gdb.ssh_gdb and fixed a few bugs, primarily with ctrl-c being ignored
Fixed bug with the getattr of the listeners
introduced a lock in `pwnlib.log` to ensure that different logging messages don't get interleaved
Another bug
changed keyword argument `non_writable` to `writable` in `pwnlib.elf.search()`.  also changed the default behaviour and updated the docstring
Updated remote_gdb_debugging.py example
Merge remote-tracking branch 'upstream/master'