doc/HACKING: removed reference to ranger/core/environment.py
config/commands.py: removed obsolete reference to fm.env
config/commands: allow going into hidden directories with :narrow
config/commands: cleaner implementation of travel.execute()
core.loader: Fix passing stdin to commands in python3
core.loader: actually kill the process when using kill_on_pause
config/commands: make :travel independent of :narrow
config/commands: remove :narrow command

The command :narrow has few use cases, which will be served by a system
that'll be implemented at a later point.
core.main: made --fail-unless-cd deprecated

Instead of launching ranger for opening files, simply use rifle.
core.main: made --mode and --flag deprecated

Again, use rifle as a file launcher instead
config/commands: update docstring of :travel
doc/ranger.1: added :travel to man page
doc/ranger.1: fully removed --mode and --flags from man page
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