PicoES v1.0.0-alpha7

• ~3x query performance boost
  • This was achieved by using callbacks instead of yield which seems to be very slow
• World initialization
  • Added new options object to World constructor, to register systems, components, and context all at once
• Simplified system context
  • Now just one object
  • Can simulate old keyed context by passing an object with one key
• Big code refactor
  • Removed indexers, but preserved concept of SimpleIndex. The memoized one was very slow in real world cases, and the interface was limiting for other types of performance improvements, while adding unnecessary complexity.
  • Split World code into SystemStorage and EntityStorage
  • More standard test code with regular jest callbacks, some more uses of expect instead of assert.
  • Deleted lots of old, unused methods throughout the code, such as prototypes, and redundant entity methods
  • Updated to use new import/export module syntax
  • Moved tests into separate directory, and made use of "files" array in package.json to shrink installed bundle size significantly.
  • Setup prettier for automated formatting

This covers fixing part of #43 , but there are still many potential improvements to make.