This makes debugging much easier,  and it also makes it possible to build
one .rpm and one .deb for all Linux-variant platforms and feature-sets.

This commit also bumps the version to 2.0.1, and updates all references
to the old sourceforge site to point to http://sflow.net.

Under src/Linux/, the loadable modules are in mod_*.c, and the framework
that loads them and allows them to communicate is in evbus.[ch].  The
evbus framework keeps activity on different threads as separate as possible,
so that in most places the code enjoys the simplicity of being effectively
single-threaded.

The Makefile no longer guesses what features you want to include.  If you
just run "make" it will try to build all the features, but if you run
something like:

  make FEATURES="DOCKER PCAP"

then only mod_docker and mod_pcap will be compiled, along with hsflowd
and the core modules.

The sflowovsd daemon has been subsumed,  and now exists as a module
in hsflowd.   To compile it,  ensure that "OVS" is in the list of features,
and that the etc/hsflowd.conf file includes an "ovs {}" section.

The /etc/hsflowd.conf file is backwards compatible,  but some fields are
deprecated.  For example,  if you have "JSONPort=36343" the new code
will suggest a change to "json { UDPPort=36343 }".