Deprecates fixed-width integer type aliases

Closes #1304 .

Author: gnzlbg

src/fixed_width_ints.rs

@@ -2,11 +2,43 @@
 //!
 //! These aliases are deprecated: use the Rust types instead.
 
+#[deprecated(
+    since = "0.2.55",
+    note = "Use i8 instead."
+)]
 pub type int8_t = i8;
+#[deprecated(
+    since = "0.2.55",
+    note = "Use i16 instead."
+)]
 pub type int16_t = i16;
+#[deprecated(
+    since = "0.2.55",
+    note = "Use i32 instead."
+)]
 pub type int32_t = i32;
+#[deprecated(
+    since = "0.2.55",
+    note = "Use i64 instead."
+)]
 pub type int64_t = i64;
+#[deprecated(
+    since = "0.2.55",
+    note = "Use u8 instead."
+)]
 pub type uint8_t = u8;
+#[deprecated(
+    since = "0.2.55",
+    note = "Use u16 instead."
+)]
 pub type uint16_t = u16;
+#[deprecated(
+    since = "0.2.55",
+    note = "Use u32 instead."
+)]
 pub type uint32_t = u32;
+#[deprecated(
+    since = "0.2.55",
+    note = "Use u64 instead."
+)]
 pub type uint64_t = u64;