std.signals regressions

[Robert]

I just finished a new implementation, replacing the template mixin with
a string mixin. I also changed the name from signals2 to signal. You can
find it here:

https://github.com/phobos-x/phobosx/blob/master/source/phobosx/signal.d

All unittests pass, you don't need any patched compiler. I still have to
add some more checks and do some polishing, I will also put it in the
dub registry. But you seem to have an urgent need, so feel free to try
it out immediately - Be my pre-alpha Tester :-)

Best regards,

Robert