bot_seen: privmsg support is lackluster

I added privmsg support as an afterthought - all the shipped bot.module plugins support it. However, if you open up a privmsg and ask the bot to "seen Morbus" or "seen frando", it happily reports " seen in 0 sec ago say" (notice the missing channel). We need to add a check off the $from_query to not log or do consider privmsgs as Seenable offenses (since Seens are displayed publicly, revealing data said in a privmsg, even though it's ridiculous, is Bad).