GLES2 renderer + Tiny updates

- Transition from GLES3 to GLES2 renderer, that has greater hardware compatibility. Hope it helps in cases where the game gets stuck on godot splash screen and more people can experience "Immortal Mantis". -Updates: [list] [*] New portrait of the policeman, to make it clear that he is injured. [*] Fixed the name "Sergei", which was previously "Serguei" [/list] Portrait preview: [img]{STEAM_CLAN_IMAGE}/42129414/7b08f44e33edc09bce3ee1de48051813cb2bfe7e.png[/img]