Minor Update - v5.2.1 - O3M3 map fix and cl_hud_alpha default value set.

Big thanks to users posting bugs on the discord; they flagged 2 issues that I've fixed.

Map O3M3: hard-lock with enemy spawning underground that couldn't be destroyed.

cl_hud_alpha: misspelled this var in the config file, meaning some users ended up with no visible HUD on a first-install.