Task split

• API breaking Task split: now there is one task for cljs-devtools and one for dirac (thank you @pepe)
• Throw if required depedencies are missing for the called task

Dirac 0.7.x

• Support for Dirac 0.7.x, thanks to @superstructor

Use :preloads and pass custom options to nRepl and Dirac

• Use the :preloads compiler options (ClojureScript >= 1.9.89 is required)
• Require boot-cljs-devtools before any other require
• Add nrepl-opts for configuring the spawned nRepl instance
• Add dirac-opts for configuring dirac