KTX file format:

Support flipped images.

Two issues here:

* We need to check the metadata for flipped flags
* We need to invert compressed images (they are stored
inverted on GPU).

Not sure if all combinations are correct here (missing reference
material to make the decision), so will assume all is OKish for now.

Merge branch 'master' into KTX_support

Conflicts:
source/blender/blenkernel/BKE_image.h
source/blender/blenkernel/intern/dynamicpaint.c
source/blender/blenkernel/intern/image.c
source/blender/blenkernel/intern/movieclip.c
source/blender/blenkernel/intern/sequencer.c
source/blender/editors/space_image/image_buttons.c
source/blender/editors/space_image/image_ops.c
source/blender/gpu/intern/gpu_draw.c
source/blender/imbuf/IMB_imbuf_types.h
source/blender/imbuf/intern/allocimbuf.c
source/blender/imbuf/intern/cineon/cineon_dpx.c
source/blender/imbuf/intern/jp2.c
source/blender/imbuf/intern/jpeg.c
source/blender/imbuf/intern/openexr/openexr_api.cpp
source/blender/imbuf/intern/png.c
source/blender/imbuf/intern/targa.c
source/blender/imbuf/intern/tiff.c
source/blender/makesrna/intern/rna_image.c
source/gameengine/Ketsji/BL_Texture.cpp

Revert conversion to long long for KTX branch

Merge branch 'temp_imbuf_types_refactor' into KTX_support

Conflicts:
source/blender/blenkernel/BKE_image.h
source/blender/blenkernel/intern/image.c
source/blender/imbuf/IMB_imbuf_types.h

Imbuf types refactor.

ImBuf types were getting stored as bitflags in a 32bit integer which had
already run out of space. Solved the problem by separating file type to
an ftype enum, and file specific options to foptions.

Now we have 2^32 image formats to support, hopefully won't run out any
time soon.

Patch is committed to branch for inclusion after release due to
increased volatility, which could result explosions, spikes, acid, lava
and signs with "bad" on them if included now.

KTX file format support

This commit introduces support for the KTX format in blender.

Saving and loading of files is supported though saving compressed formats
is not yet supported.

Thumbnails are not generated because the API relies on OpenGL to load the textures,
which is not available during threaded thumbnail generation.

We hand compiled a KTX library from https://github.com/KhronosGroup/KTX
and placed KTX lib files in intern/KTX as follows:

libktx.a in intern/KTX/lib
ktx.h in intern/KTX/include

We may include the library in extern when we make sure it compiles in all platforms (Ubuntu 15.04 failed here)

Scons is not supported, only cmake for now.