Related #1466

Related #1466

This change is not required if you use the install script to generate
~/.fzf.bash or ~/.fzf.zsh which already has the proper guard statement.

Close #1474

fzf will still override LINES and COLUMNS as before but they may not
hold the correct values depending on the default shell.

Close #1314

Close #1482

Close #1485

Close #1423

Fix #1458

* Update .travis.yml and use stages

This updates the .travis.yml configuration to use separate stages for
unittests and CLI tests. The output is now clearer, since for unittests
and CLI tests separate web pages are available.

* Use go modules and simplify build

Close #1455

Only if preview template contains {q}

Fix #1452
Related #1307

Close #867 
Close #1256 

Close #1379

Close #1393

Close #1383
Close #1384

This allows users to terminate the process with CTRL-C when it hangs.

Close #1390

Close #1356

Related:
- #612
- https://github.com/junegunn/fzf.vim/issues/308

Close #1085
Close #1086
Close https://github.com/junegunn/fzf.vim/issues/678

If an ESC char is found while processing characters,
continue to check for characters. This prevents fzf from
prematurely exiting.

Close #1349 

* Add ppc64le support to Makefile

* Update crypt libs to fix tty ioctls on ppc64le

The hardcoded tty ioctl commands in the terminal package were not
correct for ppc64le and caused the ioctls to return ENOTTY for
commands like TCGETS and so on. The bug is fixed in later versions.

* Correctly exclude SSH config options with Host

SSH config files have 14 options containing 'Host'.
Previously The zsh and bash completion scripts would include lines
containing these options when doing command-line completion of SSH hosts
with `ssh **`.

This commit fixes that problem by only including lines with 'host '.

* Don't autocomplete SSH hostnames using ?

SSH config files support ? as well as * for wildcards in Host lines.
This commit excludes lines containing ? for zsh/bash command line
completeion using `ssh **`

$FISH_VERSION is dropped in 2.7, but every version has $version

- https://github.com/fish-shell/fish-shell/issues/4414
- https://github.com/fish-shell/fish-shell/commit/fb8ae04f80c3a129f789e7b718464d014508315f

Comment from @faho in #1316:

Unfortunately, $FISH_VERSION was only ever a thing from fish 2.0 to fish 2.7.1.

All fish versions from the very beginning though used a variable called simply "$version" to store their version, so that is the one that should be used.

By implementing horizontal scrolling of the prompt line.
Maximum length is hard-coded to 300-chars.

Close #1312
Fix #1225

- Update preview window even if there is no match for the query string
  if any of the placeholder expressions evaluates to a non-empty string.
- Also, if the command template contains {q}, preview window will be
  updated if the query string changes even though the focus remains on
  the same item.

An example:

    git log --oneline --color=always |
       fzf --reverse --ansi --preview \
       '[ -n {1} ] && git show --color=always {1} || git show --color=always {q}'

Close #1307

* [bash/zsh] Fix missing fuzzy completions

`cat foo**<TAB>` did not display the file `foobar` if there was a directory
named `foo`.

Fixes #1301

* [zsh] Evaluate completion prefix

  cat $HOME**
  cat ~username**
  cat ~username/foo**

make docker
make docker-test