Optimize emplace() for arguments of the form k, v

[k3DW]

Closes #226

[cppalliance-bot]

An automated preview of the documentation is available at https://230.unordered.prtest2.cppalliance.org/libs/unordered/doc/html/unordered.html

[cppalliance-bot]

An automated preview of the documentation is available at https://230.unordered.prtest2.cppalliance.org/libs/unordered/doc/html/unordered.html

[cppalliance-bot]

An automated preview of the documentation is available at https://230.unordered.prtest2.cppalliance.org/libs/unordered/doc/html/unordered.html

[cppalliance-bot]

An automated preview of the documentation is available at https://230.unordered.prtest2.cppalliance.org/libs/unordered/doc/html/unordered.html

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (1df3705) 98.04% compared to head (bbad473) 98.06%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #230      +/-   ##
===========================================
+ Coverage    98.04%   98.06%   +0.02%     
===========================================
  Files          145      146       +1     
  Lines        19853    20038     +185     
===========================================
+ Hits         19464    19651     +187     
+ Misses         389      387       -2     

Files	Coverage Δ
...e/boost/unordered/detail/allocator_constructed.hpp	100.00% <100.00%> (ø)
...de/boost/unordered/detail/foa/concurrent_table.hpp	99.69% <100.00%> (+<0.01%)	⬆️
include/boost/unordered/detail/foa/core.hpp	99.84% <100.00%> (+<0.01%)	⬆️
...lude/boost/unordered/detail/foa/flat_map_types.hpp	100.00% <100.00%> (ø)
...lude/boost/unordered/detail/foa/node_map_types.hpp	100.00% <100.00%> (ø)
include/boost/unordered/detail/foa/table.hpp	100.00% <100.00%> (ø)
include/boost/unordered/detail/implementation.hpp	99.14% <100.00%> (+<0.01%)	⬆️
test/cfoa/emplace_tests.cpp	100.00% <100.00%> (ø)
test/helpers/count.hpp	85.48% <100.00%> (+3.51%)	⬆️
test/unordered/emplace_smf_tests.cpp	100.00% <100.00%> (ø)
... and 2 more

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1df3705...bbad473. Read the comment docs.

[cppalliance-bot]

An automated preview of the documentation is available at https://230.unordered.prtest2.cppalliance.org/libs/unordered/doc/html/unordered.html

[cppalliance-bot]

An automated preview of the documentation is available at https://230.unordered.prtest2.cppalliance.org/libs/unordered/doc/html/unordered.html

[cppalliance-bot]

An automated preview of the documentation is available at https://230.unordered.prtest2.cppalliance.org/libs/unordered/doc/html/unordered.html

[cppalliance-bot]

An automated preview of the documentation is available at https://230.unordered.prtest2.cppalliance.org/libs/unordered/doc/html/unordered.html