CppCon 2020

• feat: quantity_point support added (thanks @johelegp)
• feat: Added angle as SI base dimension (thanks @kwikius)
• feat: si::angular_velocity support added (thanks @mikeford3)
• feat: FPS system added (thanks @mikeford3)
• feat: Added support for mathematical function exp(quantity)
• feat: Localization support for text output added (thanks @rbrugo)
• feat: Added STL random number distribution wrappers (thanks @yasamoka)
• (!) refactor: Refactored and cleaned up the library file tree
• (!) refactor: q_* UDL renamed to _q_*
• (!) refactor: UDLs with "per" in name renamed from *p* to *_per_*
• (!) refactor: ratio changed to the NTTP kind
• (!) refactor: exp and Exp renamed to exponent and Exponent
• (!) refactor: Scalar concept renamed to ScalableNumber
• (!) refactor: Dimensionless quantities redesigned to be of a quantity type
• refactor: math.h function signatures refactored to use a Quantity concept (thanks @kwikius)
• refactor: [[nodiscard]] added to many functions
• fix: si::day unit symbol fixed to d (thanks @komputerwiz)
• fix: si::mole unit symbol fixed to mol (thanks @mikeford3)
• (!) build: gcc-9 is no longer supported (at least gcc-10 is required)
• build: Visual Studio 16.7 support added
• build: linear_algebra updated to 0.7.0/stable
• build: fmt updated to 7.0.3
• build: range-v3 updated to 0.11.0
• build: catch2 updated to 2.13.0
• build: doxygen updated to 1.8.18
• build: ms-gsl 3.1.0 dependency added
• build: Removed the dependency on a git submodule with common CMake scripts