Add emplace_back functions

[Nicogene]

Alongside the push_back functions we should implement the emplace_back, both in Buffer and BufferManager

[Nicogene]

Adding this feature may not be as trivial as I thought if we are going to use the boost::circular_buffer

This feature seems to be still missing see https://svn.boost.org/trac10/ticket/9299#no1 and boostorg/circular_buffer#15

[AlexAntn]

Do we need that feature though? Considering it is not present also in the circular buffer, it is likely we won't have a use for it