Builtin//misc_helpers: Various fixes (#7737)

Remove unused variable 'seplen'.
Fix 'cparam2'->'param2'.
Do not initialise variable 'p' twice.

builtin/common/misc_helpers.lua

@@ -168,7 +168,7 @@ function string.split(str, delim, include_empty, max_splits, sep_is_pattern)
 	delim = delim or ","
 	max_splits = max_splits or -1
 	local items = {}
-	local pos, len, seplen = 1, #str, #delim
+	local pos, len = 1, #str
 	local plain = not sep_is_pattern
 	max_splits = max_splits + 1
 	repeat
@@ -382,7 +382,7 @@ if INIT == "game" then
 			param2 = dirs1[fdir + 1]
 		elseif isceiling then
 			if orient_flags.force_facedir then
-				cparam2 = 20
+				param2 = 20
 			else
 				param2 = dirs2[fdir + 1]
 			end
@@ -495,7 +495,7 @@ function core.string_to_pos(value)
 		p.z = tonumber(p.z)
 		return p
 	end
-	local p = {}
+	p = {}
 	p.x, p.y, p.z = string.match(value, "^%( *([%d.-]+)[, ] *([%d.-]+)[, ] *([%d.-]+) *%)$")
 	if p.x and p.y and p.z then
 		p.x = tonumber(p.x)