Move header file to subdir
Added simple test/example, moved into subdir
Switched to variadic templates.

So instead of signal2<bool, char*>, it's now
signal<multi_thread_local, bool, char*>.

There's more work to be done of course. Firstly, I'm pretty sure some of the
heirarchy can go. Secondly, the signal template (in particular) now has a
mandatory first argument of a locking strategy. This sucks.

I don't think we really want this; I think instead we probably want something
like sigslot::mt::signal<bool, char*>, or maybe sigslot::signal_mt<..>

Also, I need to ensure that none of the locking strategies have virtual
functions unless they really need them, and a few minor tidy-ups.
Move stuff between namespaces etc
Reformatting only (tabs/spaces)
Reformatting only (tabs/spaces)
Add support for arbitrary slot functions
Make this more C++11ish, add more doc