Add deprecation notice on using

This adds a deprecation notice that will be printed on `using Formatting`,
to inform users that the package has been deprecated and that they should
consider using a different package.

Project.toml

@@ -1,11 +1,15 @@
 name = "Formatting"
 uuid = "59287772-0a20-5a39-b81b-1366585eb4c0"
-version = "0.4.2"
+version = "0.4.3"
 
 [deps]
+Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"
+Markdown = "d6f4376e-aef5-505a-96c1-9c027394607a"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 
 [compat]
+Logging = "1.11.0"
+Markdown = "1.11.0"
 julia = "1"
 
 [extras]

src/Formatting.jl

@@ -1,13 +1,24 @@
 module Formatting
 
     import Base.show
-    using Printf
+    using Printf, Logging, Markdown
 
     export
         FormatSpec, FormatExpr,
         printfmt, printfmtln, fmt, format,
         sprintf1, generate_formatter
 
+    function __init__()
+        @warn """
+        DEPRECATION NOTICE
+
+        This package has been unmaintained for a while, with some serious
+        bugs comprimising the original purpose of the package. As a result,
+        it has been deprecated - consider using an alternative, such as
+        `Format.jl` (https://github.com/JuliaString/Format.jl) or the `Printf` stdlib directly.
+        """
+    end
+
     include("cformat.jl" )
     include("fmtspec.jl")
     include("fmtcore.jl")