Easier to read lookup table for encoding using UInt8(ascii: "A") (#4)

As proposed in by @weissi in apple/swift-nio#1322
replacing the encode lookup table with uses of `UInt8(ascii: “A”)` instead of `65`
for better to read code.

Author: fabianfett

Sources/Base64Kit/Base64.swift

@@ -62,26 +62,42 @@ extension Base64 {
   // The base64 unicode table.
   @usableFromInline
   static let encodeBase64: [UInt8] = [
-     65,  66,  67,  68,  69,  70,  71,  72,
-     73,  74,  75,  76,  77,  78,  79,  80,
-     81,  82,  83,  84,  85,  86,  87,  88,
-     89,  90,  97,  98,  99, 100, 101, 102,
-    103, 104, 105, 106, 107, 108, 109, 110,
-    111, 112, 113, 114, 115, 116, 117, 118,
-    119, 120, 121, 122,  48,  49,  50,  51,
-     52,  53,  54,  55,  56,  57,  43,  47,
+    UInt8(ascii: "A"), UInt8(ascii: "B"), UInt8(ascii: "C"), UInt8(ascii: "D"),
+    UInt8(ascii: "E"), UInt8(ascii: "F"), UInt8(ascii: "G"), UInt8(ascii: "H"),
+    UInt8(ascii: "I"), UInt8(ascii: "J"), UInt8(ascii: "K"), UInt8(ascii: "L"),
+    UInt8(ascii: "M"), UInt8(ascii: "N"), UInt8(ascii: "O"), UInt8(ascii: "P"),
+    UInt8(ascii: "Q"), UInt8(ascii: "R"), UInt8(ascii: "S"), UInt8(ascii: "T"),
+    UInt8(ascii: "U"), UInt8(ascii: "V"), UInt8(ascii: "W"), UInt8(ascii: "X"),
+    UInt8(ascii: "Y"), UInt8(ascii: "Z"), UInt8(ascii: "a"), UInt8(ascii: "b"),
+    UInt8(ascii: "c"), UInt8(ascii: "d"), UInt8(ascii: "e"), UInt8(ascii: "f"),
+    UInt8(ascii: "g"), UInt8(ascii: "h"), UInt8(ascii: "i"), UInt8(ascii: "j"),
+    UInt8(ascii: "k"), UInt8(ascii: "l"), UInt8(ascii: "m"), UInt8(ascii: "n"),
+    UInt8(ascii: "o"), UInt8(ascii: "p"), UInt8(ascii: "q"), UInt8(ascii: "r"),
+    UInt8(ascii: "s"), UInt8(ascii: "t"), UInt8(ascii: "u"), UInt8(ascii: "v"),
+    UInt8(ascii: "w"), UInt8(ascii: "x"), UInt8(ascii: "y"), UInt8(ascii: "z"),
+    UInt8(ascii: "0"), UInt8(ascii: "1"), UInt8(ascii: "2"), UInt8(ascii: "3"),
+    UInt8(ascii: "4"), UInt8(ascii: "5"), UInt8(ascii: "6"), UInt8(ascii: "7"),
+    UInt8(ascii: "8"), UInt8(ascii: "9"), UInt8(ascii: "+"), UInt8(ascii: "/"),
   ]
 
   @usableFromInline
   static let encodeBase64Url: [UInt8] = [
-     65,  66,  67,  68,  69,  70,  71,  72,
-     73,  74,  75,  76,  77,  78,  79,  80,
-     81,  82,  83,  84,  85,  86,  87,  88,
-     89,  90,  97,  98,  99, 100, 101, 102,
-    103, 104, 105, 106, 107, 108, 109, 110,
-    111, 112, 113, 114, 115, 116, 117, 118,
-    119, 120, 121, 122,  48,  49,  50,  51,
-     52,  53,  54,  55,  56,  57,  45,  95,
+    UInt8(ascii: "A"), UInt8(ascii: "B"), UInt8(ascii: "C"), UInt8(ascii: "D"),
+    UInt8(ascii: "E"), UInt8(ascii: "F"), UInt8(ascii: "G"), UInt8(ascii: "H"),
+    UInt8(ascii: "I"), UInt8(ascii: "J"), UInt8(ascii: "K"), UInt8(ascii: "L"),
+    UInt8(ascii: "M"), UInt8(ascii: "N"), UInt8(ascii: "O"), UInt8(ascii: "P"),
+    UInt8(ascii: "Q"), UInt8(ascii: "R"), UInt8(ascii: "S"), UInt8(ascii: "T"),
+    UInt8(ascii: "U"), UInt8(ascii: "V"), UInt8(ascii: "W"), UInt8(ascii: "X"),
+    UInt8(ascii: "Y"), UInt8(ascii: "Z"), UInt8(ascii: "a"), UInt8(ascii: "b"),
+    UInt8(ascii: "c"), UInt8(ascii: "d"), UInt8(ascii: "e"), UInt8(ascii: "f"),
+    UInt8(ascii: "g"), UInt8(ascii: "h"), UInt8(ascii: "i"), UInt8(ascii: "j"),
+    UInt8(ascii: "k"), UInt8(ascii: "l"), UInt8(ascii: "m"), UInt8(ascii: "n"),
+    UInt8(ascii: "o"), UInt8(ascii: "p"), UInt8(ascii: "q"), UInt8(ascii: "r"),
+    UInt8(ascii: "s"), UInt8(ascii: "t"), UInt8(ascii: "u"), UInt8(ascii: "v"),
+    UInt8(ascii: "w"), UInt8(ascii: "x"), UInt8(ascii: "y"), UInt8(ascii: "z"),
+    UInt8(ascii: "0"), UInt8(ascii: "1"), UInt8(ascii: "2"), UInt8(ascii: "3"),
+    UInt8(ascii: "4"), UInt8(ascii: "5"), UInt8(ascii: "6"), UInt8(ascii: "7"),
+    UInt8(ascii: "8"), UInt8(ascii: "9"), UInt8(ascii: "-"), UInt8(ascii: "_"),
   ]
 
   @usableFromInline