more reusable "Text" object to replace "Label"

[mggower]

• cleared out index.ts file for safer import/export patterns

  • created types directory to split type definitions for internal use vs exports
  • created utils directory to split exported utils vs. internal utils

• audit type definitions

  • aligned similar type definitions, e.g. LabelStyle is now TextStyle and used by edges, labels, annotations, and text icons

• Text and TextHighlight to replace Label and LabelBackground

  • wanted to make the Label class more reusable so I can use it for text annotations

• TextTexture replaces FontBook and label utils

  • can create, destroy, or find available BitmapFont for Text objects
  • owns text style management and applies style defaults

• manage asset loading (urls, images) in object class e.g. Text and Icon