Giant optimizations:  - avoid premultipling volume by linear weight  - use a faster averaging function (twice faster than before).
Giant optimizations:
 - avoid premultipling volume by linear weight
 - use a faster averaging function
(twice faster than before).

Distrotech/DirectFB,kevleyski/directfb,Distrotech/DirectFB,mtsekm/test,dfbdok/DirectFB1,deniskropp/DirectFB,mtsekm/test,kevleyski/DirectFB-1,lancebaiyouview/DirectFB,kevleyski/directfb,lancebaiyouview/DirectFB,lancebaiyouview/DirectFB,jcdubois/DirectFB,deniskropp/DirectFB,sklnet/DirectFB,kevleyski/DirectFB-1,jcdubois/DirectFB,lancebaiyouview/DirectFB,mtsekm/test,deniskropp/DirectFB,djbclark/directfb-core-DirectFB,kevleyski/DirectFB-1,sklnet/DirectFB,dfbdok/DirectFB1,kaostao/directfb,dfbdok/DirectFB1,Distrotech/DirectFB,deniskropp/DirectFB,djbclark/directfb-core-DirectFB,DirectFB/directfb,djbclark/directfb-core-DirectFB,djbclark/directfb-core-DirectFB,sklnet/DirectFB,kevleyski/directfb,kaostao/directfb,jcdubois/DirectFB,kevleyski/DirectFB-1,kevleyski/directfb,DirectFB/directfb,sklnet/DirectFB,kaostao/directfb,DirectFB/directfb