Add copy and move to file manager.

[marksjc]

I don't use file manager here because it's limited to delete. While I regularly delete files, when I consider space issues I find many similar files, usually video, and audio files, strung across different trees (or folders, in that sense), and I don't want to delete them. I need a quick way to mark files and folders and move them. Move was not implemented on Android until fairly recently, but it improves the experience. Since I use other file managers, I've just ignored that feature here but because of the clean and speed I'd rather use this one. Movement across media is a firm requirement for this feature.