GitLab

* Extend logging in IOFetch (and add message definitions)
* Update buffer size setting for UDP socket
* remove spaces at end of lines in other files

IOFetch is a general upstream "fetch" class that should be able to
operate over TCP or UDP.  Related changes have been made in the
associated classes.  So far, only the unit tests for a UDP fetch
have been made (and passed).

Admin tasks:
* Split out io_error.h from asiolink.h
* Made test files follow naming convention of main files
* More discriminatory includes in some files
* Updates tests/Makefile.am

Coding tasks:
* Add additional methods to io_socket.* and put in dummies in
  {tcp,udp}_socket.h
* Incorporated basic IO Fetch code from Scott

briefly talked about it on jabber, no one opposed to it, Jeremy explicitly
agreed.  changes are trivial themselves, so no explicit review.

asiolink.cc are now in multiple files (ioaddress.h, iosocket.h, etc).
Also removed some shared_ptr's that weren't really needed in tcpdns
and udpdns.  This work isn't done yet, but committing now to simplify
the review a bit.



git-svn-id: svn://bind10.isc.org/svn/bind10/branches/trac327@3150 e5f2f494-b856-4b98-b285-d166d9295462