doc/ranger.1: update doc of :chmod, :delete, :find, :save_copy_buffer
config/commands: remove "--color=always" from :grep

this avoids garbled output for a pager that doesn't pass through ansi
codes to the terminal
ranger.1: update doc of :open_with
ranger.__init__: change [path/filename] to [path] in USAGE

this indicates that ranger should not be used as a file launcher
anymore, since it now ships with the standalone program `rifle'.
examples/rifle_sxiv.sh: remove bash dependency
examples/rifle_sxiv.sh: removed realpath dependency
api.commands: make DELETE_WARNING deprecated
ranger.1: added missing docs of settings
ranger.1: update list of ranger options