replace sub w/ gsub, deduplicate b64 code

src/endpoints/levels/downloadLevel.cr

@@ -58,7 +58,7 @@ CrystalGauntlet.endpoints["/downloadGJLevel22.php"] = ->(body : String): String
       response += CrystalGauntlet::Format.fmt_hash({
         1 => id,
         2 => name,
-        3 => Base64.encode(description).sub('/', '_').sub('+', '-').strip("\n"),
+        3 => GDBase64.encode(description),
         4 => level_data,
         5 => version,
         6 => user_id,

src/endpoints/levels/getLevels.cr

@@ -64,7 +64,7 @@ CrystalGauntlet.endpoints["/getGJLevels21.php"] = ->(body : String): String {
         19 => featured,
         42 => epic,
         45 => objects,
-        3 => Base64.encode(description).sub('/', '_').sub('+', '-').strip("\n"),
+        3 => GDBase64.encode(description),
         15 => length,
         30 => original || 0,
         31 => two_player,

src/endpoints/levels/uploadLevel.cr

@@ -16,7 +16,7 @@ CrystalGauntlet.endpoints["/uploadGJLevel21.php"] = ->(body : String): String {
 
   description = params["levelDesc"]
   if params["gameVersion"].to_i >= 20 # 2.0
-    description = GDBase64.decode description
+    description = GDBase64.decode_string description
   end
 
   if DATABASE.scalar("select count(*) from levels where id = ? and user_id = ?", params["levelID"], params["accountID"]).as(Int64) > 0

src/lib/format.cr

@@ -21,11 +21,15 @@ module CrystalGauntlet::GDBase64
   extend self
 
   def encode(v)
-    Base64.encode(v).sub('/', '_').sub('+', '-')
+    Base64.encode(v).gsub('/', '_').gsub('+', '-').strip("\n")
   end
 
   def decode(v)
-    Base64.decode_string(v.sub('_', '/').sub('-', '+'))
+    Base64.decode(v.gsub('_', '/').gsub('-', '+'))
+  end
+
+  def decode_string(v)
+    Base64.decode_string(v.gsub('_', '/').gsub('-', '+'))
   end
 end
 

src/lib/gjp.cr

@@ -7,7 +7,7 @@ module CrystalGauntlet::GJP
   XOR_KEY = "37526"
 
   def decrypt(pass : String)
-    pwd = Base64.decode(pass.sub('_', '/').sub('-', '+'))
+    pwd = GDBase64.decode(pass)
     decrypted = ""
 
     pwd.each.with_index() do |chr, index|
@@ -24,7 +24,7 @@ module CrystalGauntlet::GJP
       encrypted[index] = chr ^ XOR_KEY.byte_at(index % XOR_KEY.bytesize)
     end
 
-    Base64.encode(encrypted).sub('/', '_').sub('+', '-')
+    GDBase64.encode(encrypted)
   end
 
   def hash(pass : String)