CmdStan installation

Minimal requirement

To run this version of the Stan.jl package on your local machine, it assumes that the CmdStan executable is properly installed.

In order for Stan.jl to find the CmdStan executable you can

1.1) set the environment variable CMDSTAN_HOME to point to the CmdStan directory, e.g. add

export CMDSTAN_HOME=/Users/rob/Projects/Stan/cmdstan
launchctl setenv CMDSTAN_HOME /Users/rob/Projects/Stan/cmdstan

to .bash_profile. I typically prefer not to include the cmdstan version number in the path so no update is needed when CmdStan is updated.

Currently tested with CmdStan 2.16.0.

Optional requirements

By default Stan.jl uses Mamba.jl for diagnostics and graphics.

1. Mamba
2. Gadfly

Both packages can be installed using Pkg.add(), e.g. Pkg.add("Mamba"). It requires Mamba v"0.10.0". Mamba will install Gadfly.jl.

The Stanmodel field useMamba can be set to false to disable the use of Mamba and Gadfly.

Additional OSX options

Thanks to Robert Feldt and the brew/Homebrew.jl folks, on OSX, in addition to the user following the steps in Stan's CmdStan User's Guide, CmdStan can also be installed using brew or Julia's Homebrew.

 Executing in a terminal:
 ```
 brew tap homebrew/science
 brew install cmdstan
 ```
 should install the latest available (on Homebrew) cmdstan in /usr/local/Cellar/cmdstan/x.x.x
 
 Or, from within the Julia REPL:
 ```
 using Homebrew
 Homebrew.add("homebrew/science/cmdstan")
 ```
 will install CmdStan in ~/.julia/v0.x/Homebrew/deps/usr/Cellar/cmdstan/x.x.x.