merge changes for 3.7.21 release

.hgtags

doc/contributions.txt

indra/llrender/llshadermgr.cpp

indra/llwindow/llopenglview-objc.h

indra/llwindow/llopenglview-objc.mm

indra/llwindow/llwindowmacosx.cpp

indra/newview/VIEWER_VERSION.txt

...wview/app_settings/shaders/class1/avatar/avatarSkinV.glsl

...wview/app_settings/shaders/class1/avatar/objectSkinV.glsl

...view/app_settings/shaders/class1/deferred/blurLightF.glsl

...pp_settings/shaders/class1/deferred/multiPointLightF.glsl

...app_settings/shaders/class1/deferred/multiSpotLightF.glsl

...newview/app_settings/shaders/class1/deferred/postgiF.glsl

...view/app_settings/shaders/class1/deferred/spotLightF.glsl

...app_settings/shaders/class2/deferred/multiSpotLightF.glsl

...view/app_settings/shaders/class2/deferred/spotLightF.glsl

indra/newview/llappdelegate-objc.mm

indra/newview/lldrawpoolavatar.cpp

indra/newview/llfilepicker.cpp

indra/newview/llmaniprotate.cpp