Fix broken preview border. Reported by Thomas Sattler.

    fzf --bind 'enter:execute(date)' --preview=date --reverse

Due to the recent removal of ncurses dependency, we can cross-compile
binaries for different platforms without virtual machines.

Goes well with --height

Due to performance consideration, FuzzyMatchV2 does not return the exact
positions of the matching characters by default. However, the ommission
caused `--tiebreak=begin` to produce inaccurate result in some cases.

  (echo baz foo bar; echo foo bar baz) | fzf --tiebreak=begin -fbar | head -1

  # Expected: foo bar baz
  # Actual:   baz foo bar

This commit fixes the problem by using the end offset which is
guaranteed to be correct.

https://github.com/junegunn/go-runewidth/pull/1

/cc @joshuarubin

- Move cursor to the top-left corner when starting a command in
  alternate screen
- Fix cursor position when returning to alternate screen when fzf is
  running in full screen mode

Close #825

Close #823

Close #788

Close #822

Close #821

Close #820

Close #497

Close #818

- Remove unnecessary scrolling
- Allow us to use `--height 100%` under Neovim terminal for 24-bit colors

Related:
- #789
- https://github.com/neovim/neovim/issues/4151

Also revert the workaround in Vim plugin introduced in fa7c8977.

Related: #814

Close #816

Close #805

Close #781