Build instructions for macOS

[Bryan Haley]

Building on macOS is very similar; would be nice if it was included in the readme.

Prereqs:

• xcode-select --install (this installs the xcode command line tools including compilers, libraries, etc).
• brew install glew cmake (needed libraries not already in macOS)

Building and installing:

• cd build
• cmake ..
• make
• sudo make install
• sudo update_dyld_shared_cache

[GreenALan]

i have xcode-select and glew cmake,
but when i make, it give me error: use of
undeclared identifier 'GL_STATIC_DRAW'

i make it failed

[Libra star]

在编译安装的过程中, sudo: ldonfig: command not found