Remove fz_context from pdf_crypt

Unused field. Also tweak some comments for clarity.
Remove duplicated XPS definitions from header.
Bug 694831: Check width and height of bitmap, not width and width

Thanks to Dale King for reporting this.
Bug 694810: Fix crash when clicking on mupdf window after failed page load.

If we have a NULL page, don't attempt to pass events to it.
Android: a few improvements to the view handling

While scrolling, avoid some overheads to do with image scaling that
need updating only on a zoom-level change

Remove a pointless invalidate call.

Avoid calls to removeViewInLayout and removeAllViewsInLayout that
were being made in functions not called from onLayout
Solve subpixel rendering problems with 270 degree rotations

It seems that (int)-98.5 = 98, not -99. Use floorf instead.