Some pre/post related stuff

Reload the onesix version config after the commands (addresses https://www.pivotaltracker.com/story/show/60360652)
Add a few more variables and also substitute them in the command (fixes https://www.pivotaltracker.com/story/show/66994828)

logic/MinecraftProcess.h

@@ -131,6 +131,13 @@ protected:
 	QString launchScript;
 	QString m_nativeFolder;
 
+	bool preLaunch();
+	bool postLaunch();
+	QMap<QString, QString> getVariables() const;
+	QString substituteVariables(const QString &cmd) const;
+
+	QStringList javaArguments() const;
+
 protected
 slots:
 	void finish(int, QProcess::ExitStatus status);