KDE dragon player collides with the name of the drag/drop dependency. On
archlinux the binary is renamed to `dragon-drag-and-drop`.

This change tries `dragon-drag-and-drop` before defaulting to `dragon`.

* Added 2 plugins for drag and drop support

These scripts uses https://github.com/mwh/dragon
and curl.

It allows nnn to drag and drop files either to other programs, or to
itself.

* added link to dependency and spelling

* added drag/drop-file scripts to readme table

* Implemented edit selection buffer

* Added checks and changed keybind

* Forgot check and style fixes

* Don't work late at night again

You forget things when you're tired

allow multiple make targets being specified at once

do build configuration with variables instead of targets

This reverts commit e226e8c889.