Release 1.22

• More robust handling of Ctrl+C in benchexec.
  For example, output files are now always fully written, whereas previously pressing Ctrl+C at the wrong time could result in truncated files. A side effect of this is that if you call benchexec.benchexec.BenchExec().start() in own Python code, you must now add a signal handler for SIGINT. The same was already true for users of RunExecutor, this is now documented.
• Fix Ctrl+C for benchexec in container mode.
  In BenchExec 1.21, one would need to press Ctrl+C twice to stop benchexec.
• Fix unreliable container mode on Python 3.7.
• Some robustness improvements and fixes of rare deadlocks.
• Decreased overhead of benchexec while runs are executing.