Address #277: Allow setting max history-size for FileHistory.

[timmc]

For #277. Two parts:

• Add delayed-init constructor for FileHistory so that setMaxSize can be called before load (otherwise backing file is truncated)
• Expose ConsoleReader.getInputRc to allow retrieval of history-size variable from inputrc for use in FileHistory.setMaxSize

[timmc]

For reference, here's what the integration looks like from my working branch of a relying Clojure project:

(defn ^Integer default-history-size
  "Get default history size from system settings, or nil if not set.
Set `app-name` for jline's reading of inputrc, or null for default."
  [app-name]
  (try
    (-> (ConsoleKeys. app-name (ConsoleReader/getInputRc))
        (.getVariable "history-size")
        (Integer/parseInt))
    (catch IOException ioe
      (binding [*out* *err*]
        (println "Error retrieving history size for REPL-y:" ioe))
      nil)))

(defn configure-history
  "Configure a MemoryHistory or FileHistory's max-size, if non-nil."
  [hist size]
  (when size
    (.setMaxSize hist size)))

...
(doto (FileHistory. (make-history-file history-file) false)
  (configure-history (default-history-size))
  (.load))
...