ptvsd release v4.2.0

Enhancements:

• Support multi-process debugging for spawned processes.
• Add support for monkey-patching pyside2.

Bug Fixes:

• Properly deal with handled or unhandled exception in top level frames. #580, #581
• Use unhandled exception line when creating stack. #814
• Use SO_EXCLUSIVEADDRUSE on windows while creating socket. #820
• Check if exit code is none before converting to int. #840
• Add messages to error responses. #826
• Make sure that any folder ending with site-packages is considered a library. #854
• Allow configuring whether the debugger should stop/print errors when there's an exception evaluating a breakpoint condition. #853
• Treat any code not in site-library as user code. #802
• Fix to preserve frame and variable ids while stepping. #870 , #907
• Handle case where no completions are provided by the debugger. #978
• Set SIO_LOOPBACK_FAST_PATH while creating socket in windows. #912, #949