Fix clang compiler error

error: non-constant-expression cannot be narrowed from type 'unsigned
int' to 'int' in initializer list [-Wc++11-narrowing]
note: override this message by inserting an explicit cast -> done
timer.h: use header file instead of forward declaration
callback is now a class with variadic template

The new callback class should be used instead of the old ones.
It has a lot of benefits, e.g. more than 6 parameter, lambda expressions
can be used but also old function/member pointer.
The old callbacks are typedefs (using) for now, but may be later
removed.

The syntax of a callback is equal to the syntax of a std::function, e.g.
callback<int(int, std::string)>, which is pretty nice.

Testing was done as far as I could do, namely compile the whole
clanlib-lib and all examples. They compiled and ran fine.
added "Documentation" to callback
add generic signal class
removed unneeded files

instead of the old slot class you should now use a callback (instance,
reference, pointer, whatever). You can do exactly the same things as
with the Slot class. You can enable (connect) disable (disconnect) and
destroy (clear) it.
add operator== to callback.h
fixed using typo in signal
callback.h: fix template deduction

the compiler (clang 3.4) cannot deduct the template argument for the
constructor. So instead of delegating the c'tor implement it. I don't
know if one can fix the original problem, but this will solve it for
now.
signal.h: fixed invoke method

I forgot to add the const specifier.
add signal.h to makefile.am
changed all old signal handler to the new one

In fact it just was removing some slot/slot variables and use the new
initializer lists (they are awesome {!})
add #warning for callback headers
fixed all signal/callback imports

I just did:
 * sed -ri 's:signal_v.\.h:signal.h:g' **.{h,cpp}
 * sed -ri 's:callback_..?\.h:callback.h:g' **.{h,cpp}
in the Sources folder
cleanup of callback/signal headers

removed old callback/signal headers
removed typedefs
added move constructor
add callbackcontainer as a replacement of slotcontainer
fixed const correctness in callback
finally fixed segfault in new callback class

I think the main error was to store a reference to the signal/callback.
Now I store a copy of it and everything works fine.
Also work on a copy in the invoke method (in signal) so you can safely
remove (disconnect) callbacks from the signal
replaced every occurrence of old signal/slot

The new callback/signal class is now totally integrated in the clanlib
sources. Only the examples and documentation is left over. Will be done
soon.
adopted display examples to new callbackcontainer