compatability.h needs review

[NooneAtAll]

Is your feature request related to a problem? Please describe.

"compatability.h" is a file made to fix GCC compiler versions
before 4.8 due to flag (MinGW) and newlib (Cygwin) issues
(std::to_string was not provided)

As current minimal GCC version supported is 5.3, most code
in the file regarding MinGW is not used.

After extensive googling I have found several mentions of
CygWin not giving the error with -std=c++11 and -std=c++14
flags. (later of which is what is used in this codebase)

Describe the solution you'd like

Some testing needed whether whole file, parts of it or at least Cygwin build
flag can be deleted.

[stale]

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[stale]

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