No Signal.Alarm on Windows

The misc module imports alarm from signal.
This is however not available on Windows (https://docs.python.org/2/library/signal.html#signal.alarm).
As a result, the misc module cannot be loaded and an (incorrect) error message is shown:
Failed to load module: No module named misc
Other modules are loaded just fine, but mavproxy no longer responds to anything that is entered.

Start by inspecting the misc module and its signal import, focusing on why importing alarm prevents the module from loading on Windows. Reproduce the module-loading failure on Windows, then verify that misc loads without the incorrect error and MAVProxy responds to entered commands.

Written by the indexing model from the issue text.