webapp: rename load_single_project to switch_to_project
webapp: rename load_single_project to switch_to_project

tscholl2/smc,tscholl2/smc,DrXyzzy/smc,sagemathinc/smc,tscholl2/smc,DrXyzzy/smc,DrXyzzy/smc,tscholl2/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc,sagemathinc/smc,sagemathinc/smc