With the current way that the `HandTool` is implemented, if someone would try to also add a Zoom tool (as issue 1260 asks for) that probably wouldn't work very well given that you'd then have two cursor tools which may not play nice together.
Hence this patch, which attempts to refactor things so that it should be simpler to add e.g. a Zoom tool as well (given that that issue is marked as "good-beginner-bug", and I'm not sure if that really applies considering the current state of the code).
Note that I personally have no interest in implementing a Zoom tool (similar to Adobe Reader) since I wouldn't use it, but I figured that it can't hurt to make this code a bit more future proof.
Note that as discussed on IRC, this makes the viewer slightly slower to load *only* in `gulp server` mode, however the difference seem slight enough that I think it will be fine.
There's really no good reason to attempt to adjust the `max-height` of the `SecondaryToolbar` when it's not visible, so let's not do that anymore.
Also, we can listen for the `resize` event in `SecondaryToolbar`, to avoid having to manually call the `max-height` adjust function from various event handlers in `app.js`. Please note that by always adjusting the `max-height` when the toolbar is opened we no longer need the `localized` event, since it was mainly used to set a correct inital `max-height` value.
This patch:
- Simplifies the way fields are passed to the document properties overlay
- Simplifies the way fields are filled internally in the document properties overlay
- Avoids passing a document properties reference to the secondary toolbar
This patch:
- Adds a couple of utility methods to `PDFViewer` to enable checking `presentationModeState` without cumbersome comparisons.
- Disentangles `PresentationMode` from `PDFHistory` and `HandTool`, by adding event listeners for `presentationmodechanged` to both of them.
- Adds a utility function to `PDFViewerApplication` for requesting PresentationMode.
- Prevents initialization of `PresentationMode` if the browser does not support the fullscreen API.
