support persistent and in-pager search history

[stephentalley]

I'm really enjoying moving from less to moar. Thanks for your work!

However, one feature of less that I miss is the ability to search for several different patterns, then typing "/" and hitting up/down to select a search string from history.

less also supports $LESSHISTFILE, which allows those saved searches to persist beyond a single invocation of less.

It would be nice if moar could support this as well.