Add cast to silence warning when building with -Wconversion
Fix memset size in getPixel()
Merge pull request #9 from davvid/memset-size

Fix memset size in getPixel()
Optimize mipmap level calculation (don't use log2f)
Fix regression in encodeDifference

introduced in commit ba46a5
Change regression tests to use uint16

Exercises differencing code.  (float/half don't use differencing)
PtexFilter.cpp: add explicit casts to silence -Wconversion warnings

Signed-off-by: David Aguilar <davvid@gmail.com>
Merge pull request #10 from davvid/conversion-warnings

PtexFilter.cpp: add explicit casts to silence -Wconversion warnings