nano: Add a plus variant with more features
Nano is by default built as "tiny" with most features disabled.
That is suitable for basic tasks in routers with small flash.
Add a new nano-plus variant that enables selected additional
features in the build config:
* multiple files (multibuffer)
* Unicode/utf8
* justify
* .nanorc support
* help
* also some key bindings get enabled as "tiny" configure option
is removed.
Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>
(cherry picked from commit
85cb71d8d81af3c549406d5f42080ed58be9b9b0)