Remove the original timers that were deprecated a while back

[jeking3]

Looking at http://www.boost.org/doc/libs/1_65_1/libs/timer/doc/index.html, it looks like there could be some code simplification by removing the original timers.

[pdimov]

Good idea in principle. I've marked these headers as deprecated in 075d6b2. Hopefully they would become removable in a few releases (there are still too many uses of them in tests, and one in Boost.Test.)

[jeking3]

It's been deprecated since at least 1.53.0:
https://www.boost.org/doc/libs/1_53_0/libs/timer/doc/index.html

I guess this is the next step, making it noisy....