update unicode string escape sequences for 1.3

Prior to this commit exmoji used the old `\x{H*}` format for unicode
escape sequences, which generates warnings with Elixir 1.3. This commit
updates those escape sequences to use the preferred `\xHH` and `\uHHHH`
formats.

lib/exmoji.ex

@@ -183,7 +183,7 @@ defmodule Exmoji do
       iex> Exmoji.char_to_unified("👾")
       "1F47E"
 
-      iex> Exmoji.char_to_unified("\x{23}\x{fe0f}\x{20e3}")
+      iex> Exmoji.char_to_unified("\x23\u{fe0f}\u{20e3}")
       "0023-FE0F-20E3"
 
   """

test/emoji_char_test.exs

@@ -31,18 +31,18 @@ defmodule EmojiCharTest do
   end
 
   test ".render - should have flag to output forced emoji variant char encoding if requested", examples do
-    assert EmojiChar.render(examples[:cloud], variant_encoding: false) == "\x{2601}"
-    assert EmojiChar.render(examples[:cloud], variant_encoding:  true) == "\x{2601}\x{FE0F}"
+    assert EmojiChar.render(examples[:cloud], variant_encoding: false) == "\u2601"
+    assert EmojiChar.render(examples[:cloud], variant_encoding:  true) == "\u2601\uFE0F"
   end
 
   test ".render - should fall back to normal encoding if no variant exists, even when requested", examples do
-    assert EmojiChar.render(examples[:invader], variant_encoding: false) == "\x{1F47E}"
-    assert EmojiChar.render(examples[:invader], variant_encoding:  true) == "\x{1F47E}"
+    assert EmojiChar.render(examples[:invader], variant_encoding: false) == "\u{1F47E}"
+    assert EmojiChar.render(examples[:invader], variant_encoding:  true) == "\u{1F47E}"
   end
 
   test ".render - should default to variant encoding for chars with a variant present", examples do
-    assert EmojiChar.render(examples[:cloud])     == "\x{2601}\x{FE0F}"
-    assert EmojiChar.render(examples[:hourglass]) == "\x{231B}\x{FE0F}"
+    assert EmojiChar.render(examples[:cloud])     == "\u2601\uFE0F"
+    assert EmojiChar.render(examples[:hourglass]) == "\u231B\uFE0F"
   end
 
 
@@ -51,7 +51,7 @@ defmodule EmojiCharTest do
   #
   test ".chars - should return an array of all possible string render variations", examples do
     assert EmojiChar.chars(examples[:invader]) == ["👾"]
-    assert EmojiChar.chars(examples[:cloud])   == ["\x{2601}","\x{2601}\x{FE0F}"]
+    assert EmojiChar.chars(examples[:cloud])   == ["\u2601","\u2601\uFE0F"]
   end
 
 

test/exmoji_test.exs

@@ -156,7 +156,7 @@ defmodule ExmojiTest do
   end
 
   test ".char_to_unified - converts variant encoded emoji to variant unified codepoint" do
-    assert Exmoji.char_to_unified("\x{2601}\x{FE0F}") == "2601-FE0F"
+    assert Exmoji.char_to_unified("\u{2601}\u{FE0F}") == "2601-FE0F"
   end
 
 
@@ -174,11 +174,11 @@ defmodule ExmojiTest do
   end
 
   test ".unified_to_char - converts variant unified codepoints to unicode strings" do
-    assert Exmoji.unified_to_char("2764-fe0f") == "\x{2764}\x{FE0F}"
+    assert Exmoji.unified_to_char("2764-fe0f") == "\u{2764}\u{FE0F}"
   end
 
   test ".unified_to_char - converts variant+doublebyte chars (triplets!) to unicode strings" do
-    assert Exmoji.unified_to_char("0030-FE0F-20E3") == "\x{0030}\x{FE0F}\x{20E3}"
+    assert Exmoji.unified_to_char("0030-FE0F-20E3") == "\u{0030}\u{FE0F}\u{20E3}"
   end
 
 end

test/scanner_test.exs

@@ -4,9 +4,9 @@ defmodule ScannerTest do
   alias Exmoji.Scanner
 
   @case_exact         "🚀"
-  @case_multi         "\x{0023}\x{FE0F}\x{20E3}"
+  @case_multi         "\u{0023}\u{FE0F}\u{20E3}"
   @case_variant       "flying on my 🚀 to visit the 👾 people."
-  @case_multivariant  "first a \x{0023}\x{FE0F}\x{20E3} then a 🚀"
+  @case_multivariant  "first a \u{0023}\u{FE0F}\u{20E3} then a 🚀"
   @case_duplicates    "flying my 🚀 to visit the 👾 people who have their own 🚀 omg!"
   @case_none          "i like turtles"