Add String() methods to types, so they can be printed with %s. Change
some %s format specifiers to %v, when the default string representation
is good enough. In Go 1.10, `go test` triggers a parallel `go vet`. So
this also makes fzf pass `go test`.

Close #1236
Close #1219

* Document inverse prefix exact match search syntax.

* Reorder search syntax table to explain basic exact match first.

Close #1216

1. Append a single space so that step 3 won't fail
2. CTRL-E to move to the end of the line
3. CTRL-U to delete the whole line before the cursor
4. CTRL-Y to paste the deleted line
5. ESC+Y to rotate the kill ring and bring back the previous yank before step 3
6. CTRL-U to delete the whole line again
7. Paste `__fzf_history__`
8. ESC+CTRL-E to expand the command substitution
9. ESC+R to redraw the line
10. ESC+^ to expand the history entry (!NUMBER)

For now, they are respectively bound to preview-up and preview-down
by default (TBD).

Not available on tcell build.

Close #1201

Close #1203

Fix #1205

I've decided not to take more donations.

Thanks to everyone who has supported my projects.

Edgar Hipp
Eyal Levin
Philip Stewart
James O'Beirne
Minh Triet Ly
Victor Alvarez
Max Hung
Gearoid Murphy
Aaron Taylor
Brett Bender
Phil Thompson
Anders Damsgaard

Close #681

Close #1172

This reverts commit 2f1edeff.

- Close #1169
- https://github.com/gdamore/tcell/pull/159

The issue is fixed in https://github.com/vim/vim/commit/1232624ae5b56c167c5982a2620f736c4bbc19ef

After _completion_loader is called, instead of loading the entire
completion.bash file, just restore the fzf completion for the current
command. `_fzf_orig_completion_$cmd` is only set if _completion_loader
actually changed the completion options to avoid infinite loop.

Close #1170

'accept-non-empty' is similar to 'accept' (which is bound to 'enter' and
'double-click' by default) but it prevents fzf from exiting without any
selection.

Close #1162

replace-query action replaces the query string with the current
selection. If the selection is too long, it will be truncated.

If the line contains meta-characters of fzf search syntax, it is
possible that the line is no longer included in the updated result.

e.g.

  echo '!hello' | fzf --bind ctrl-v:replace-query

Close #1137

Close #1168

left-click and right-click are respectively bound to "ignore" and
"toggle" (after implicitly moving the cursor) by default.

Close #1130

In #1061 we changed the default command to retry with a simpler find
command with fewer arguments if the first find command failed. This was
to support stripped-down verions of find that do not support -fstype
argument.

However, this caused an unwanted side-effect of yielding duplicate
entries when the first command failed after producing some lines.

We revert the change in this commit, so the default command will not
work with find without -fstype support. But we now print better error
message in that case so that the user can set up a working
$FZF_DEFAULT_COMMAND.

Close #1120 #1167

/cc @ehandal

Close #1152

msys2 terminal Vim assumes that it runs in mintty
so `:terminal` uses `TERM=xterm`.
fzf doesn't support `TERM=xterm` on Windows.

Fixes #915

The `Respecting .gitignore` link pointed to a section of the readme which no longer exists.

- https://github.com/sharkdp/fd
- https://mike.place/2017/fzf-fd/

/cc @williamsmj

On Cygwin and MinGW, the fzf binary will have a .exe extension, so
ignore that binary if it exists as well as the bare binary.