Add GMTL - Generic Math Template Library recipe

[psyinf]

Specify library name and version: gmtl/0.7.1

The library is originally hosted at an sourceforge svn repository. It's however no longer maintained by the original authors. I've added some minor corrections and plan on further developing the library and make it available to a broader audience by adding it to conan.
Despite its age and relatively low maintenance in the last years I've used it over the last 10-15 years in various hobby- and professional projects. This is my first attempt to contribute to conan and I'd be happy to get some guidance.

---

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the conan-center hook activated.

[CLAassistant]

All committers have signed the CLA.

[jwillikers]

Oops, wrong button. Still need some changes. Did you register for access on CCI @psyinf ?

[uilianries]

Please, remove all comments from the template. It's documented to be removed: https://github.com/conan-io/conan-center-index/blob/master/docs/package_templates/cmake_package/all/conanfile.py#L15

[psyinf]

Overall its super good!

Just a few point

• clean up from templates
• expose official targets (there a question about your intentions for how this fork is used in there)

I left all the suggestions, I hopefully did break anything 🤞

Thank you very much for reviewing. Highly appreciated!

[conan-center-bot]

Conan v1 pipeline

All green in build 28 (ceb2ca9cffd5bc8f5684fc69737fad009106b307):

• psyinf-gmtl/0.7.1@:
  All packages built successfully! (All logs)

[SpaceIm]

names in CMakeDeps & cmake_find_package[_multi] are not consistent

[psyinf]

I just tried to use the recipe with cmake multi environment. Do we need to set
self.cpp_info.names["cmake_find_package"] = "gmtl"
self.cpp_info.names["cmake_find_package_multi"] = "gmtl"
to use it as a drop-in replacement?

Also, should'nt I use
self.cpp_info.set_property("cmake_target_name", "gmtl::gmtl") ?

[SpaceIm]

1.50.0 is enough