Work around GCC5 compiling error in cuboid_rectangle.h (another approach to #42464)

[Qrox]

Summary

SUMMARY: Build "Work around gcc 5 compiling error in cuboid_rectangle.h"

Purpose of change

In gcc 5, when clamp is called with explicit template argument int, clamp in cuboid_rectangle.h conflicts with clamp in cata_utility.h and a static_assert error is displayed. According to SFINAE, clamp in cuboid_rectangle.h should be discarded, which is also the behavior of all other compilers. #42464 fixed it by casting arguments instead of using explicit template argument, but it made code more verbose just for the sake of a particularly old compiler.

Describe the solution

Revert #42464 and work around the compiling error by checking for parent class / class member's existence in the template parameter list. Unfortunately this means that the classes in cuboid_rectangle.h cannot be foward declared.

Describe alternatives you've considered

Dump gcc 5.3 support?

Testing

I used compiler explorer to test this change and it seemed to work with every major compiler. It still displays a static_assert message when it should, instead of displaying some obscure template error message.

[Qrox]

It is working now. Travis mingw-w64 fails on tests in units_test.cpp which is unrelated, LGTM fails when building the master branch because There is not enough space on the disk, so that's probably an error in LGTM itself.