Add 'get' canvas functions to ranges

[MImranAsghar]

• Add getCanvases, getCanvasById, getCanvasByIndex functions for the range type

[stephenwf]

I'm not sure why, but 3 tests appear to be failing now:

195 passing (2s)
  3 failing
  1) pres3 presentation 3 range has a canvas:
     TypeError: Cannot read property '__jsonld' of undefined
      at context.<anonymous> (test/tests/pres3.js:48:96)
  2) pres3 presentation 3 has an annotation body:
     TypeError: Cannot read property 'getContent' of undefined
      at context.<anonymous> (test/tests/pres3.js:54:26)
  3) pres3 presentation 3 has a label:
     TypeError: Cannot read property 'getLabel' of undefined
      at context.<anonymous> (test/tests/pres3.js:62:26)

[MImranAsghar]

Ah interesting, looking into it 👍

[MImranAsghar]

Hi @stephenwf , fixed the tests

[MImranAsghar]

Hi @stephenwf , I was wondering if you got a chance to take a look at the changes. do you think this can be merged? 🤔

[stephenwf]

Sorry yes I think so 👍 @edsilv ?