Makefile: Fixed "PHONY" stuff
Fixed tab completion of "open_with" command
Makefile: Added info about DESTDIR in "make options"
api.apps: Fix handling of single-string return values
Feature: pasting hardlinked trees

This feature is useful when there is a need to create a directory tree,
which is similar to an existing one while keeping all the files in this
new tree hardlinked to those existing ones. Such functionality might be
useful when rearranging a huge directory tree (or a set of directory
trees) into some new layout.

This operation is done synchronously (i.e. it doesn't use CommandLoader
to put the ongoing operation into the task queue).

Target end of the operation is handled the following way:

1. If target directory with the same name exists - it gets used.

2. If target folder does not exist - it is created with the same mode
   bits as corresponding source one.

3. If target file with the same name exists and is a hardlink of the
   source file already - it is getting left as it is. If it's not a
   hardlink of the source file - a new hardlink is created in a form of
   <original>_, <original>_1, ..., etc.

4. If target file does not exist - a hardlink is created.
ranger.1: fix vim script "RangerChooser" when no file is opened

https://savannah.nongnu.org/bugs/?35556
gui.ui: Added "rxvt-unicode-256color" to TERMINALS_WITH_TITLE
Removed unnecessary spaces
Added "sudo" optional dependency to README
Catch a trivial ncurses exception
Added $RANGER_LEVEL environment variable (see man page)
Merge branch 'master' into stable
Fix crash when opening files with feh or sxiv with "ranger <image>"
Always remember to bring your towel.
scope.sh: added exiftool
gui.ui: catch an exception with surrogates in "update title" code
shorten all copyright messages for better readability
ext.human_readable: added comment
defaults/options: add __pycache__ to hidden files
data/mime.types: use spaces instead of tabs, line them up