Bools and returns super-pr (#53221)

Replaces like 70-80% of 0 and such, as a side effect cleaned up a bunch of returns
Edit: Most left out ones are in mecha which should be done in mecha refactor already
Oh my look how clean it is

Co-authored-by: TiviPlus <TiviPlus>
Co-authored-by: Couls <coul422@gmail.com>

code/modules/modular_computers/computers/item/computer.dm

@@ -222,11 +222,11 @@
 /obj/item/modular_computer/process()
 	if(!enabled) // The computer is turned off
 		last_power_usage = 0
-		return 0
+		return
 
 	if(obj_integrity <= integrity_failure * max_integrity)
 		shutdown_computer()
-		return 0
+		return
 
 	if(active_program && active_program.requires_ntnet && !get_ntnet_status(active_program.requires_ntnet_feature))
 		active_program.event_networkfailure(0) // Active program requires NTNet to run but we've just lost connection. Crash.

code/modules/modular_computers/computers/item/computer_ui.dm

@@ -7,17 +7,17 @@
 	if(!enabled)
 		if(ui)
 			ui.close()
-		return 0
+		return
 	if(!use_power())
 		if(ui)
 			ui.close()
-		return 0
+		return
 
 	// Robots don't really need to see the screen, their wireless connection works as long as computer is on.
 	if(!screen_on && !issilicon(user))
 		if(ui)
 			ui.close()
-		return 0
+		return
 
 	// If we have an active program switch to it now.
 	if(active_program)
@@ -74,9 +74,9 @@
 	data["programs"] = list()
 	var/obj/item/computer_hardware/hard_drive/hard_drive = all_components[MC_HDD]
 	for(var/datum/computer_file/program/P in hard_drive.stored_files)
-		var/running = 0
+		var/running = FALSE
 		if(P in idle_threads)
-			running = 1
+			running = TRUE
 
 		data["programs"] += list(list("name" = P.filename, "desc" = P.filedesc, "running" = running))
 

code/modules/modular_computers/computers/item/laptop.dm

@@ -17,7 +17,7 @@
 	// No running around with open laptops in hands.
 	item_flags = SLOWS_WHILE_IN_HAND
 
-	screen_on = 0 		// Starts closed
+	screen_on = FALSE 		// Starts closed
 	var/start_open = TRUE	// unless this var is set to 1
 	var/icon_state_closed = "laptop-closed"
 	var/w_class_open = WEIGHT_CLASS_BULKY

code/modules/modular_computers/computers/item/processor.dm

@@ -43,13 +43,6 @@
 /obj/item/modular_computer/processor/relay_qdel()
 	qdel(machinery_computer)
 
-// This thing is not meant to be used on it's own, get topic data from our machinery owner.
-//obj/item/modular_computer/processor/canUseTopic(atom/movable/M, be_close=FALSE, no_dexterity=FALSE, no_tk=FALSE)
-//	if(!machinery_computer)
-//		return 0
-
-//	return machinery_computer.canUseTopic(user, state)
-
 /obj/item/modular_computer/processor/shutdown_computer()
 	if(!machinery_computer)
 		return