TypeDesc: add handy is_vec3 and is_vec4 methods
Timer: make a lap_ticks() method
Minor simd.h tweaks
simd - minor tweaks
Add an option to link against static ilmbase and openexr libraries, taking care to link in the proper order so that all necessary symbols are included
GIF input plug: Fix build with giflib>=5.1

From giflib-5.1.0's NEWS:
"A small change to the API: DGifClose() and EGifClose() now take a
pointer-to-int second argument (like the corresponding openers)
where a diagnostic code will be deposited when they return
GIF_ERROR."
Support for movie files, using ffmpeg.
Individual frames look like "subimages" to OIIO.
Exclude too-old ffmpeg installations. Also suppress console warnings.
Fix compile errors on MSVS2013.

Our working theory is that one of the MSVS headers has a #define of IN or
OUT. So we change the names of the types in our template, and people report
that it compiles.

Fixes #974
Merge branch 'master' of https://github.com/OpenImageIO/oiio into metadata
fix std min missing issue
fix bad gps data issue