update package names and licence

This updates the package name to include the major API version (0), and the licence to assign copyright holder to files.

I am going to respond to some of the suggestions from the original wnpp (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=988116).

libdecor-0-0 should probably have Recommends: libdecor-plugin-1-cairo | libdecor-plugin-1 so that third-party plugins (if any) can Provides: libdecor-plugin-1

At the moment, the plugin API is private and all plugins are maintained in-tree. This might change later, when the API is stabilised.

The version of the MIT/X11 license quoted here is called "Expat" in d/copyright files, to distinguish it from the many other licenses used by MIT and X11.

I think this copyright file was created by some debhelper script that parsed all source files and gathered the licences and copyright holders. The "libdecor-cairo-blur.{c,h}" files are taken from the Weston project. They have the same licence (MIT, https://opensource.org/licenses/MIT) but different copyright holders. I updated the file and associated the copyright holder to the files.

I think all shared library packages should have at least a superficial autopkgtest

Is the purpose of this to test that the library be correctly linked etc. or only to check that all header and library files have been installed? Does this test run when the package is created or when it is installed at the user?