Raises character slot limit to 30 (#3089)

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## About The Pull Request

![imagen](https://github.com/shiptest-ss13/Shiptest/assets/75212565/9dd55f82-55d4-47c6-b1f9-bf6597d78cf6)
mark was wrong god save us all

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## Why It's Good For The Game
You know how we encourage playing different characters for the multiple
factions?

Currently, we have 6 player factions (CLIP, PGF, NT, SRM, Inteq, SolCon)
plus 6 branches of the Syndicate (ACLF, Cybersun, Hardliners, SUNS, NGR,
GEC) and 2 special factions (Fronties, Ramzi). If I wanted two
characters for each faction (officer, assistant, medic, whatever) and
one for each special faction, I'd need 26 slots. 40 seems good.

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## Changelog

:cl:
add: Character slots have been raised to 40. BYOND members get 50.
/:cl:

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---------

Signed-off-by: rye-rice <[email protected]>
Co-authored-by: rye-rice <[email protected]>

code/modules/client/preferences.dm

@@ -5,7 +5,7 @@ GLOBAL_LIST_EMPTY(preferences_datums)
 	//doohickeys for savefiles
 	var/path
 	var/default_slot = 1				//Holder so it doesn't default to slot 1, rather the last one used
-	var/max_save_slots = 20
+	var/max_save_slots = 30
 
 	//non-preference stuff
 	var/muted = 0
@@ -227,7 +227,7 @@ GLOBAL_LIST_EMPTY(preferences_datums)
 			load_path(C.ckey)
 			unlock_content = C.IsByondMember()
 			if(unlock_content)
-				max_save_slots = 30
+				max_save_slots = 50
 	var/loaded_preferences_successfully = load_preferences()
 	if(loaded_preferences_successfully)
 		if(load_character())