Client-side autojump. Remove Android-only stepheight autojump (#7228)

Works by detecting a collision while moving forward and then
simulating a jump. If the simulated jump is more successful,
an artificial jump key press is injected in the client.

Includes setting and key change GUI element for enabling and
disabling this feature.

src/player.cpp

@@ -144,6 +144,7 @@ void PlayerSettings::readGlobalSettings()
 	always_fly_fast = g_settings->getBool("always_fly_fast");
 	aux1_descends = g_settings->getBool("aux1_descends");
 	noclip = g_settings->getBool("noclip");
+	autojump = g_settings->getBool("autojump");
 }
 
 void Player::settingsChangedCallback(const std::string &name, void *data)