move all modals into src/ui/modals/.
added rect-modal.jsx. Much duplicate code from position-modal.
remove unused import.
add PhaserState.Generators.makeInertStateObject.
added top, left fields to rect-modal.
added width, height fields to rect-modal.
if sprites have a 'spawnArea' prop, randomly spawn them within it.
user can now choose between fixed/random sprite spawn point.