Updates compiling.md.
Updates compiling.md.

- Adds new section for project references

- Changes ES6 references to ES2015 

- Updates Testing section to recent changes in plugins
markek/Fable,fable-compiler/Fable,markek/Fable,fable-compiler/Fable,mastoj/Fable,fable-compiler/Fable,inosik/Fable,fable-compiler/Fable,ncave/Fable,fable-compiler/Fable,ncave/Fable,ncave/Fable,ncave/Fable,fable-compiler/Fable,ncave/Fable,ncave/Fable,markek/Fable,fable-compiler/Fable,ncave/Fable,inosik/Fable,mastoj/Fable,mastoj/Fable