Improve the curve editor rendering
Improve the curve editor rendering

- Fix grid rendering when using a light theme
- Enable anti-aliasing for the main curve line
  (only applies when using the GLES3 renderer)
- Swap the main line and edge line colors for better visibility
- Scale some line widths on hiDPI displays
  (not all of them could be scaled due to rendering bugs)

Zylann/godot,akien-mga/godot,Paulloz/godot,vkbsb/godot,vnen/godot,vkbsb/godot,DmitriySalnikov/godot,ZuBsPaCe/godot,vkbsb/godot,Paulloz/godot,Faless/godot,sanikoyes/godot,Zylann/godot,akien-mga/godot,josempans/godot,Faless/godot,josempans/godot,guilhermefelipecgs/godot,Zylann/godot,godotengine/godot,BastiaanOlij/godot,DmitriySalnikov/godot,honix/godot,Paulloz/godot,sanikoyes/godot,BastiaanOlij/godot,vnen/godot,MarianoGnu/godot,MarianoGnu/godot,ZuBsPaCe/godot,josempans/godot,vkbsb/godot,honix/godot,DmitriySalnikov/godot,Valentactive/godot,Faless/godot,Shockblast/godot,guilhermefelipecgs/godot,Valentactive/godot,godotengine/godot,firefly2442/godot,ex/godot,ex/godot,godotengine/godot,guilhermefelipecgs/godot,josempans/godot,BastiaanOlij/godot,Paulloz/godot,MarianoGnu/godot,firefly2442/godot,firefly2442/godot,MarianoGnu/godot,firefly2442/godot,guilhermefelipecgs/godot,ex/godot,Zylann/godot,ZuBsPaCe/godot,firefly2442/godot,pkowal1982/godot,guilhermefelipecgs/godot,firefly2442/godot,pkowal1982/godot,Valentactive/godot,Valentactive/godot,Valentactive/godot,Shockblast/godot,josempans/godot,pkowal1982/godot,sanikoyes/godot,Shockblast/godot,akien-mga/godot,pkowal1982/godot,akien-mga/godot,akien-mga/godot,sanikoyes/godot,Shockblast/godot,ex/godot,Paulloz/godot,vkbsb/godot,MarianoGnu/godot,honix/godot,ex/godot,Shockblast/godot,BastiaanOlij/godot,firefly2442/godot,BastiaanOlij/godot,vnen/godot,pkowal1982/godot,ZuBsPaCe/godot,vnen/godot,Paulloz/godot,Faless/godot,akien-mga/godot,Shockblast/godot,guilhermefelipecgs/godot,honix/godot,Valentactive/godot,Valentactive/godot,Faless/godot,ZuBsPaCe/godot,sanikoyes/godot,sanikoyes/godot,Zylann/godot,ex/godot,MarianoGnu/godot,akien-mga/godot,Shockblast/godot,honix/godot,vnen/godot,MarianoGnu/godot,godotengine/godot,godotengine/godot,Paulloz/godot,sanikoyes/godot,DmitriySalnikov/godot,vnen/godot,josempans/godot,guilhermefelipecgs/godot,akien-mga/godot,DmitriySalnikov/godot,sanikoyes/godot,DmitriySalnikov/godot,godotengine/godot,DmitriySalnikov/godot,vkbsb/godot,Faless/godot,guilhermefelipecgs/godot,godotengine/godot,MarianoGnu/godot,ZuBsPaCe/godot,Zylann/godot,Zylann/godot,pkowal1982/godot,BastiaanOlij/godot,firefly2442/godot,Faless/godot,Zylann/godot,BastiaanOlij/godot,honix/godot,pkowal1982/godot,Shockblast/godot,vnen/godot,Faless/godot,vkbsb/godot,Valentactive/godot,BastiaanOlij/godot,ZuBsPaCe/godot,vkbsb/godot,godotengine/godot,vnen/godot,josempans/godot,josempans/godot,ex/godot,pkowal1982/godot,ex/godot,ZuBsPaCe/godot