Make `--doctool` imply `--headless` to speed up class reference generation
Make `--doctool` imply `--headless` to speed up class reference generation

This also prevents spawning an unnecessary splash screen window
while the class reference is generated.

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