Android: fix build
Android: for scroll steps, use postOnAnimation when available

Using postOnAnimation in place of post noticably improves scroll
smoothness. Also avoid posting multiple runnables unnecessarily.
fix various MSVC warnings

Some warnings we'd like to enable for MuPDF and still be able to
compile it with warnings as errors using MSVC (2008 to 2013):

* C4115: 'timeval' : named type definition in parentheses
* C4204: nonstandard extension used : non-constant aggregate initializer
* C4295: 'hex' : array is too small to include a terminating null character
* C4389: '==' : signed/unsigned mismatch
* C4702: unreachable code
* C4706: assignment within conditional expression

Also, globally disable C4701 which is frequently caused by MSVC not
being able to correctly figure out fz_try/fz_catch code flow.

And don't define isnan for VS2013 and later where that's no longer needed.
fix MSVC warnings C4054 and C4152

These warnings are caused by casting function pointers to void*
instead of proper function types.
tolerate slightly broken page trees

At https://code.google.com/p/sumatrapdf/issues/detail?id=2460 , there's
a file with missing /Type keys in the page tree nodes. In that case,
leaf nodes and intermediary nodes have to be distinguished in a
different way.
add stub files for JPEG-XR support

See SumatraPDF's repo for a Windows-only implementation using WIC.
show jbig2dec warnings/errors in stderr

This helps debugging issues with JBIG2 images.

Conflicts:

	source/fitz/filter-jbig2.c
reuse JBIG2Globals

Certain optimized documents use a rather large common symbol dictionary
for all JBIG2 images. Caching these JBIG2Globals speeds up loading and
rendering of such documents.