Minor code cleanup for readability.
Cleanup: more spelling var-names, wrap long lines, fix debug-levels, ...

... remove duplicate log messages, save intention-levels.
Cleanup parsing and handling of first line in received datagram.
Cleanup parsing header lines into headers fields.
Cleanup redundant code.
Add test before unregistering if service to be unregistered is registered.
Update copyright header.
Prefix private methods/attributes with underscore.
More spelling method name.
Ensure some attribute always exist.

These are tested for "not None" in shutdown(), but are not always set.
Well, maybe the test in shutdown should have been removed instead.
Cleanup: Move some code outside the try-block.

This may never raise the exception which is caught.
Enh: Make utils.parse_http_response return the content, too.

While this is not used yet, it may be useful sometimes and is nearly for
free.
Cleanup parsing HTTP responses.

This is basically porting
2014-06-02T17:06:26Z!h.goebel@crazy-compilers.com and
2014-06-02T17:16:06Z!h.goebel@crazy-compilers.com to
utils.parse_http_response().
Use utils.parse_http_response() for parsing HTTP responses.

This is what I was looking for in
2014-06-02T17:06:26Z!h.goebel@crazy-compilers.com and
2014-06-02T17:16:06Z!h.goebel@crazy-compilers.com, but did not see
this code.
Cleanup: Import constant value instead of defining it twice.
Rearrange some code to make it easier to understand.
Prefix private methods/attributes with underscore.
Refactor: Move shutdown-like code into the SSDP/MSeach classes.
Cleanup: Move some code outside the try-block.

Because if this part fails, we have a programming error.
Minimalistic cleanup.