Restructured alien removal surgery.

This way it later can be used for lung surgery.

code/modules/mob/living/carbon/carbon_defines.dm

@@ -2,7 +2,7 @@
 	gender = MALE
 	var/list/stomach_contents = list()
 	var/brain_op_stage = 0.0
-	var/embryo_op_stage = 0
+	var/ribcage_op_stage = 0
 /*
 	var/eye_op_stage = 0.0
 	var/appendix_op_stage = 0.0
@@ -19,4 +19,4 @@
 	var/analgesic = 0 // when this is set, the mob isn't affected by shock or pain
 					  // life should decrease this by 1 every tick
 	// total amount of wounds on mob, used to spread out healing and the like over all wounds
-	var/number_wounds = 0
+	var/number_wounds = 0