v0.2.1

Very powerful update!

Improved Side Effect Scripts

• Integrated into the declare_resources! macro.
• The hooks notify the component when they are ready.
• A new <ScriptEffect/> component that allows easy conditional execution.
  see here for a guide

declare_resources! Macro Overhaul

All expressions like macro/identifier/function call can be used as resource URLs now, with explicitly specified resource type