Actually renames 'going' var.

Axes speed of light and procs that used it (but were not used by anything). More maths too, and max stack amounts, not used anywhere.
Ticks back stuff that was unticked for faster compile, whoops.

code/__defines/atmos.dm

@@ -83,7 +83,4 @@
 
 //Flags for zone sleeping
 #define ZONE_ACTIVE   1
-#define ZONE_SLEEPING 0
-
-#define SPEED_OF_LIGHT       3e8    // Approximate.
-#define SPEED_OF_LIGHT_SQ    9e16
+#define ZONE_SLEEPING 0

code/__defines/math_physics.dm

@@ -1,7 +1,5 @@
 // Math constants.
-#define M_E     2.71828183
 #define M_PI    3.14159265
-#define M_SQRT2 1.41421356
 
 #define R_IDEAL_GAS_EQUATION       8.31    // kPa*L/(K*mol).
 #define ONE_ATMOSPHERE             101.325 // kPa.

code/__defines/misc.dm

@@ -132,11 +132,6 @@
 #define CUSTOM_ITEM_SYNTH 'icons/mob/custom_synthetic.dmi'
 #endif
 
-// Metal sheets, glass sheets, and rod stacks.
-#define MAX_STACK_AMOUNT_METAL 50
-#define MAX_STACK_AMOUNT_GLASS 50
-#define MAX_STACK_AMOUNT_RODS  60
-
 #define WALL_CAN_OPEN 1
 #define WALL_OPENING 2