Load main scene if defined when running editor from the command line

If no main scene is defined, or if it's an empty string, the previous behaviour will still be used, i.e. launch the project manager.
A small fix was also added not to maximize the window when opening the project manager via -editor (i.e. "godot" and "godot -e" will behave the same when no project is in the path).

Fixes #2869.

main/main.cpp

@@ -432,7 +432,6 @@ Error Main::setup(const char *execpath,int argc, char *argv[],bool p_second_phas
 		} else if (I->get()=="-e" || I->get()=="-editor") { // fonud editor
 
 			editor=true;
-			init_maximized=true;
 		} else if (I->get()=="-nowindow") { // fullscreen
 
 			OS::get_singleton()->set_no_window_mode(true);
@@ -649,6 +648,7 @@ Error Main::setup(const char *execpath,int argc, char *argv[],bool p_second_phas
 
 	if (editor) {
 		main_args.push_back("-editor");
+		init_maximized=true;
 		use_custom_res=false;
 	}
 
@@ -1093,7 +1093,7 @@ bool Main::start() {
 
 #endif
 
-	if(script=="" && game_path=="" && !editor && String(GLOBAL_DEF("application/main_scene",""))!="") {
+	if(script=="" && game_path=="" && String(GLOBAL_DEF("application/main_scene",""))!="") {
 		game_path=GLOBAL_DEF("application/main_scene","");
 	}
 

tools/editor/project_manager.cpp

@@ -624,11 +624,6 @@ void ProjectManager::_open_project_confirm() {
 
 		args.push_back("-editor");
 
-		const String &selected_main = E->get();
-		if (selected_main!="") {
-			args.push_back(selected_main);
-		}
-
 		String exec = OS::get_singleton()->get_executable_path();
 
 		OS::ProcessID pid=0;