Add some scripts for getting character usage info

CharacterInfoExtraction/UniqueCharacters.swift

@@ -0,0 +1,24 @@
+import Foundation
+
+var standardError = FileHandle.standardError
+
+extension FileHandle : TextOutputStream {
+	public func write(_ string: String) {
+		guard let data = string.data(using: .utf8) else { return }
+		self.write(data)
+	}
+}
+
+guard CommandLine.arguments.count > 1 else {
+	print("Usage: \(CommandLine.arguments[0]) file\nUse - to read from stdin", to: &standardError)
+	exit(EXIT_FAILURE)
+}
+let input: String
+if CommandLine.arguments[1] == "-" {
+	input = String(decoding: FileHandle.standardInput.readDataToEndOfFile(), as: UTF8.self)
+} else {
+	input = try String(contentsOf: URL(fileURLWithPath: CommandLine.arguments[1]))
+}
+let chars = Set(input.unicodeScalars)
+let out = chars.sorted().lazy.map(Character.init)
+print(String(out), terminator: "")