Added so char can be converted to int128

spec/std/char_spec.cr

@@ -237,31 +237,37 @@ describe "Char" do
     '1'.to_i16.should eq(1i16)
     '1'.to_i32.should eq(1i32)
     '1'.to_i64.should eq(1i64)
+    '1'.to_i128.should eq(1i128)
 
     expect_raises(ArgumentError) { 'a'.to_i8 }
     expect_raises(ArgumentError) { 'a'.to_i16 }
     expect_raises(ArgumentError) { 'a'.to_i32 }
     expect_raises(ArgumentError) { 'a'.to_i64 }
+    expect_raises(ArgumentError) { 'a'.to_i128 }
 
     'a'.to_i8?.should be_nil
     'a'.to_i16?.should be_nil
     'a'.to_i32?.should be_nil
     'a'.to_i64?.should be_nil
+    'a'.to_i128?.should be_nil
 
     '1'.to_u8.should eq(1u8)
     '1'.to_u16.should eq(1u16)
     '1'.to_u32.should eq(1u32)
     '1'.to_u64.should eq(1u64)
+    '1'.to_u128.should eq(1u128)
 
     expect_raises(ArgumentError) { 'a'.to_u8 }
     expect_raises(ArgumentError) { 'a'.to_u16 }
     expect_raises(ArgumentError) { 'a'.to_u32 }
     expect_raises(ArgumentError) { 'a'.to_u64 }
+    expect_raises(ArgumentError) { 'a'.to_u128 }
 
     'a'.to_u8?.should be_nil
     'a'.to_u16?.should be_nil
     'a'.to_u32?.should be_nil
     'a'.to_u64?.should be_nil
+    'a'.to_u128?.should be_nil
   end
 
   it "does to_i with 16 base" do

src/char.cr

@@ -722,7 +722,7 @@ struct Char
     to_i?(base)
   end
 
-  {% for type in %w(i8 i16 i64 u8 u16 u32 u64) %}
+  {% for type in %w(i8 i16 i64 i128 u8 u16 u32 u64 u128) %}
     # See also: `to_i`.
     def to_{{type.id}}(base : Int = 10)
       to_i(base).to_{{type.id}}