Corrected boost bind deprecation warning

[jeppefrandsen]

Fixes issue #98

[jeppefrandsen]

@mat007 can you have a look? Thanks a lot 🍻

[mat007]

I haven’t been following Boost lately (as in «in the past 5 years or so» 😁), what’s the difference between boost/bind.hpp and boost/bind/bind.hpp? Do you have a link that explains why including the latter does not issue a deprecation warning?

[mat007]

Also they are other includes to boost/bind.hpp, should they not be updated as well?
See https://github.com/mat007/turtle/search?q=bind.hpp

[jeppefrandsen]

@mat007 you can read more here https://stackoverflow.com/questions/53203970/why-boostbind-insists-pulling-boostplaceholders-into-global-namespace but makes sense to update the tests as well at some point (will see if I can find a bit of time) but caused build issues as first.

[Flamefire]

Fixed as a side effect of #88
Thanks anyway!

[jeppefrandsen]

Great @Flamefire 🍻