Current state

PDF documents have a print direction and a display direction.
A landscape document may be displayed incorrectly (90deg rotated) in the current pdfviewer.

Desired improvement

add a autoRotate property to pdfviewer (true by default).

apply the rotation by default (follow pdf.js behavior)
the viewer should add the page rotation info to the component's own rotation when loading a page.

let viewport = page.getViewport({scale: this._zoom, rotation: this._rotation}),

becomes:

let viewport = page.getViewport({scale: this._zoom, rotation: this._rotation + page._pageInfo.rotate }),

in Pdfviewer.ts#L455