How to configure which folders are compiled when SuperCollider sclang starts up

sclanguageconfig

This piece of info is buried deep in help, and difficult to find. 

However it is quite handy:  It saves you from having to copy or to put aliases of folders with your own class definitions
into the SuperCollider user app support dir / Extensions folder. 

Instead you add paths of folders like this: 

LanguageConfig.addIncludePath("...");

And you can exclude paths that cause problems like this: 

LanguageConfig.addExcludePath("...");

!!!!!!!!!!!!!! IMPORTANT: 
However, before recompiling you have to run the following to save the changed config: 

LanguageConfig.store;