New D2D API calls and upgrades to tests-d2d and pong

[JohnDog3112]

• New D2D API calls:
  • cToImageData in place of imageData (which now has a deprecated warning)
  • getCanvasProp String and Double variants
  • setCanvasProp String and Double variants
• Upgrades to tests-d2d
  • Added new API calls as tests
  • added a test to check for memory leaks in the API calls
  • This check just runs every test twice and ensures the available memory after both tests is the same
  • Moved test name strings to C and added functions for JS to reference them
• Removed test cases from Pong in favor of tests-d2d
• Fixed memory leak in API caused by adding a second heap_ptr for setCanvasPropString