A new plugin called "rmodifier" (for "Regex modifier") has been added.

It's designed to change some strings using regex, for example to hide passwords in commands (input displayed on screen) or in history. By default, password in following commands are hidden by this plugin:

• /msg nickserv identify ****** (input and history)
• /msg nickserv ghost ****** (input and history)
• /oper nick ****** (input and history)
• /set file.section.password ****** (history only)

Of course you can add your own regex, just look at /help rmodifier.

Updated on 2014-08-15: the plugin rmodifier has been replaced by trigger, introduced in version 1.0.