Fix auto-completion for `/`

Close #456 and #457

Pass FZF_DEFAULT_OPTS to non-interactive bash instance

The size of pseudo-terminal in Travis CI environment can be small

Close #451

Fix CTRL-T in tmux

Instead of choosing one at initialization, choose the correct one
when it's actually called, so that the behavior is correct even after
resizing.

Bonus fixes for tmux with bash 4+:
- No extra space when cancelling CTRL-T.
- Fix cursor position problem in vi mode.

- Don't assume ~/.fzf.bash exists.
- Source the current script for __fzf_select__.
- Forward $PATH.

Correct fzf-tmux tmux checking bug

Support fzf-tmux when zoomed

Having submodules causes vim-plug or other vim plugin managers to clone
them with no real benefit to the end-users. There's currently no
compelling reason for me to use submodules.

Related: https://github.com/junegunn/fzf.vim/issues/49

Add android build: `make android`

Close #425. Thanks to @blueyed.

zsh: fzf-completion: use noshwordsplit local option

This also fixes the completion causing a bell / flickering in case
"shwordsplit" was not set, because then the function would return false.

zsh completion: use \grep to skip any alias

Related: #373

Close #412

Close #413