merge changes for 4.0.7-release

.hgtags

doc/contributions.txt

indra/llcommon/indra_constants.cpp

indra/llcommon/indra_constants.h

indra/llcommon/llstring.cpp

indra/llcommon/llstring.h

indra/llimage/llimage.cpp

indra/llimage/llimage.h

indra/llimage/llimagebmp.cpp

indra/llimage/llimagebmp.h

indra/llimage/llimagedxt.cpp

indra/llimage/llimagedxt.h

indra/llimage/llimagej2c.cpp

indra/llimage/llimagej2c.h

indra/llimage/llimagejpeg.cpp

indra/llimage/llimagejpeg.h

indra/llimage/llimagepng.cpp

indra/llimage/llimagepng.h

indra/llimage/llimagetga.cpp

indra/llimage/llimagetga.h