Automate protocol decoder installation.

Automate protocol decoder installation.

This automatically figures out the files to install for each protocol
decoder, without involving autotools.

All python files (filenames ending in .py) are always installed. If a
protocol decoder requires installation of a non-python file, a small
file called 'config' can be created in that protocol decoder's
directory, with the following content:

	# comments are ok
	extra-install vendorlist.txt commands.txt