Add function glm_perspective_lh_zo

This commit adds the function `glm_perspective_lh_zo`, modelled on the
implementation of glm_perspective, but amended to provide a left-hand
coordinate system expected by DirectX, Metal and Vulkan (per the GLM
project's `glm/detail/setup.hpp`). It uses a clip-space of zero-to-one.

The function is tested against a longhand version of the algorithm it
seeks to implement as well as against the output of the GLM project's
`glm::perspectiveLH_ZO` function. This commit adds a new subdirectory
`test/glm_cmp` which contains a basic CMake file and `main.cpp`. An
interested user should link or copy or clone the GLM project into this
directory. The `main` function can be used to print the reference data
used so others can verify behaviour in the future, or add new literal
reference values.

.gitignore

@@ -76,3 +76,5 @@ build/
 conftest.dir/*
 confdefs.h
 *.xcuserdatad
+.idea
+cmake-build-debug