Import pdfs

[pihart]

Resolves #69

[pihart]

Currently doesn't give right output for LaTeX documents (this seems to be a font issue), works well on some qboard documents, errors on other qboard documents with

TypeError
Cannot read property 'appendChild' of null
Call Stack
 push../node_modules/fabric/dist/fabric.js.fabric.ElementsParser.push../node_modules/fabric/dist/fabric.js.proto.resolveClipPath
  main.app.js:9557:32
 push../node_modules/fabric/dist/fabric.js.fabric.ElementsParser.push../node_modules/fabric/dist/fabric.js.proto.resolveClipPath
  main.app.js:9578:14
 undefined
  main.app.js:9510:13
 undefined
  main.app.js:25458:19
 HTMLImageElement.onLoadCallback
  main.app.js:5530:30

and on other documents with

Error
[object ProgressEvent]
Call Stack
 rejectionHandler
  main.app.js:1140:21

which expands to

ProgressEvent {isTrusted: true, lengthComputable: true, loaded: 0, total: 2956587, type: "error", …}
bubbles: false
cancelBubble: false
cancelable: false
composed: false
currentTarget: FileReader
  error: DOMException: The requested file could not be read, typically due to permission problems that have occurred after a reference to a file was acquired.
  onabort: null
  onerror: ƒ ()
  onload: () => { resolve(reader.result); }
  onloadend: null
  onloadstart: null
  onprogress: null
  readyState: 2
  result: null
  __proto__: FileReader
defaultPrevented: false
eventPhase: 0
isTrusted: true
lengthComputable: true
loaded: 0
path: []
returnValue: true
srcElement: FileReader
  error: DOMException: The requested file could not be read, typically due to permission problems that have occurred after a reference to a file was acquired.
  onabort: null
  onerror: ƒ ()
  onload: () => { resolve(reader.result); }
  onloadend: null
  onloadstart: null
  onprogress: null
  readyState: 2
  result: null
  __proto__: FileReader
target: FileReader
  error: DOMException: The requested file could not be read, typically due to permission problems that have occurred after a reference to a file was acquired.
  onabort: null
  onerror: ƒ ()
  onload: () => { resolve(reader.result); }
  onloadend: null
  onloadstart: null
  onprogress: null
  readyState: 2
  result: null
  __proto__: FileReader
timeStamp: 12414.589999942109
total: 2956587
type: "error"
__proto__: ProgressEvent

[cjquines]

bumping this; this seems relevant for promys xp

[pihart]

Wait for #180. Drop from ccb68cf to afee6f0 and rebase d6a8b98 on top of the result of #180.