Describe radix-k algorithm.

ietAddTile raises ICET_INVALID_VALUE if you try to create a tile with no
pixels.

icetFindRankInGroup, icetFindMyRankInGroup

The following state variables are not set with sequential strategy:
ICET_ALL_CONTAINED_TILES_MASKS, ICET_TILE_CONTRIB_COUNTS, and
ICET_TOTAL_IMAGE_COUNT.

Suggest using sequential strategy for single tile (because it skips some
allgathers).

icetCommBarrier

icetImageAssignBuffer, icetSingleImageAssignBuffer

icetWaitany returns index to finished request - different than MPI.

icetCommGather, icetCommGatherV

ICET_IN_PLACE_COLLECT

ICET_SIZE_TYPE (list of types in implement new strategy -> Communications).

const array for compose_group in single image strategy functions.

icetSingleImageCompose interface change.

icetSingleImageCollect.

General change to single image strategy functions.

ICET_MAGIC_K state variable, CMake variable, and environment variable.

icetCompressedCompressedComposite

icetSparseImageCopyPixels

icetSparseImageSplit

icetSparseImageSplitPartitionNumPixels

icetImageEqual, icetSparseImageEqual

icetDecompressSubImage

icetRenderTransferSparseImages

icetSparseImageNull, icetSparseImageIsNull

icetUnsafeStateGet* now return const

todo: correct background before gather

ICET_INTERLACE_IMAGES

icetSparseImageInterlace

ICET_MAGIC_K environment variable

ICET_COLELCT_TIME: The fraction of ICET_COMPOSITE_TIME spent in collecting
image fragments to display process.
