Add ability to remember custom combination of search flags in seek and scan files

[Gregg Young]

If you would, would you do a patch to "fix" the seek and scan sayfiles problem a bit better? What I would like to have is the last setting remembered. You can steal the code for the RememberExt setting from extract.c. I would name the setting "grep.sayfiles" unless that's already used.

We should identify any other menu items that will benefit from the same treatment and add tickets for them.A