Fix mistakes after previous merge and make it compile.
Rewrite the function interpolating between time stamps as it was
written after the original pull request was created. Add unit tests
for it.
I couldn't help myself and also changed some enums to enum classes and
did some renames.
There exists `CreateDirectory` `#define` somewhere and it results in
failed compilation of `resourcemanager.cpp`.
Similarly for `RemoveDirectory`. See
https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createdirectorya
Rename the two methods to remove the conflict.
The fail occurs at least when using Visual Studio 2022 Preview.
-Wmissing-declarations enforces that every function (except for static
functions) must be declared separately before it's defined. This
essentially enforces that every function must be either static, or
declared in a header elsewhere.
This helps the optimizer, as it can do a better job of inlining if it
knows that a function won't be used outside of a given file. It also
helps -Wunused-function (which is enabled by -Wall) find more unused
functions.
Note that Clang spells this option -Wmissing-prototypes, which
confusingly is the name of a related but different warning option under
GCC.
MrSimbax