Compatible with Python 3

Make chisel compatible with Python 3 (#266)

* Make chisel compatible with Python 3

Xcode 11 shipped with Python 3 now. Unfortunately, chisel was written in
Python 2 style and will fail load for lldb. This PR fixed the Python 3
compatibility issues.

* Addressed comment. Updated with file output.

* Properly resolve the conflict.

* Import from future on print.

* Address @lsavino comment.