sdl/i_main.c: while we're here, split all the logging initialisation code into a separate function, to make main function more clean

(though that said we don't officially care about the win32 folder files anymore)

V_Init: count to NUMSCREENS, not NUMSCREENS+1 (though I can't help thinking this one might have been deliberate somehow?)

Polyobj_rotate and related: change "origin" to vector2_t since all it needs is x/y and not any of the new stuff for vertex_t

This way, if for some reason the ghost has no skin, nothing should spawn at all

added missing extern keyword for ms_RoomId in mserv.h (the definition is already in the .c file in this case)

turn all non-extern variables in s_sound.h into externs (and put their real definitions in the .c file)

This fixes act names not being shown on player 2's view

Last minute OpenGL fix: don't check flippedness in HWR_RotateSpritePolyToAim if the mobj is actually a precipmobj!

precipmobj_t does not have eflags, so P_MobjFlip checking it would actually be accessing memory addresses beyond the end of the struct

These fixes were suggested by Sveciaost on #mac-users on Discord