Default PanoramaSkyMaterial texture to black instead of white
Default PanoramaSkyMaterial texture to black instead of white

This prevents blinding the user while the user is still setting up
the panorama sky texture.

josempans/godot,vkbsb/godot,Shockblast/godot,sanikoyes/godot,Shockblast/godot,akien-mga/godot,Valentactive/godot,vkbsb/godot,Valentactive/godot,Valentactive/godot,godotengine/godot,godotengine/godot,vkbsb/godot,guilhermefelipecgs/godot,Zylann/godot,guilhermefelipecgs/godot,pkowal1982/godot,josempans/godot,Zylann/godot,firefly2442/godot,pkowal1982/godot,BastiaanOlij/godot,pkowal1982/godot,ZuBsPaCe/godot,vkbsb/godot,akien-mga/godot,godotengine/godot,BastiaanOlij/godot,BastiaanOlij/godot,vkbsb/godot,BastiaanOlij/godot,Valentactive/godot,firefly2442/godot,guilhermefelipecgs/godot,ZuBsPaCe/godot,BastiaanOlij/godot,sanikoyes/godot,ZuBsPaCe/godot,ZuBsPaCe/godot,Shockblast/godot,pkowal1982/godot,akien-mga/godot,sanikoyes/godot,akien-mga/godot,Shockblast/godot,ZuBsPaCe/godot,akien-mga/godot,vkbsb/godot,firefly2442/godot,ZuBsPaCe/godot,BastiaanOlij/godot,sanikoyes/godot,firefly2442/godot,Valentactive/godot,pkowal1982/godot,godotengine/godot,guilhermefelipecgs/godot,godotengine/godot,josempans/godot,Zylann/godot,firefly2442/godot,sanikoyes/godot,pkowal1982/godot,Valentactive/godot,Zylann/godot,vkbsb/godot,ZuBsPaCe/godot,josempans/godot,ZuBsPaCe/godot,pkowal1982/godot,guilhermefelipecgs/godot,firefly2442/godot,godotengine/godot,sanikoyes/godot,Zylann/godot,guilhermefelipecgs/godot,akien-mga/godot,vkbsb/godot,Shockblast/godot,firefly2442/godot,josempans/godot,BastiaanOlij/godot,Valentactive/godot,guilhermefelipecgs/godot,sanikoyes/godot,godotengine/godot,Zylann/godot,josempans/godot,Zylann/godot,akien-mga/godot,Shockblast/godot,Zylann/godot,akien-mga/godot,Shockblast/godot,pkowal1982/godot,sanikoyes/godot,Shockblast/godot,guilhermefelipecgs/godot,josempans/godot,godotengine/godot,firefly2442/godot,josempans/godot,Valentactive/godot,BastiaanOlij/godot