mpv: update waf to 1.7.16

This commit follows mpv-player/mpv@86e5f15592d2c732c03735f4aa7d6361ee0f20dd.
mpv: 0.4.0

Release 0.4.0
https://github.com/mpv-player/mpv/releases/tag/v0.4.0
mpv: always install zsh completion
Point to new homebrew-cask repository
Merge pull request #31 from kalin/master

README: point to new homebrew-cask repository
mpv: add an option to disable installing zsh completion
mpv: 0.4.1
mpv: doesn't support DVD and Blu-ray anymore

This commit follows mpv-player/mpv@4b93210e0c
Revert "mpv: doesn't support DVD and Blu-ray anymore"

This reverts commit 44959e2d3717789936ce3aa57a72f0dbdc8847f4.
This follows mpv-player/mpv@23a7257cca.
mpv: change install path of mpv.app

Homebrew also changes the shared library identification name of a
dynamic shared library in #{previx}/{bin, lib and Frameworks}, so we
have to change install path of mpv.app to avoid the overwriting.
mpv: fix brew audit complaints
libass-ct: fix audit error
mpv: cosmetic changes

Use Pathname#/ (aliased to join) instead of #+
mpv: fix zsh completion option semantic

Default to building the zsh completions. This was erroneously changed to
defaulting to not building them in commit fc67bcfe0.
Revert "mpv: fix zsh completion option semantic"

This reverts commit 396daa8eca9d07029e7702a444a4832df831444d.
mpv: add '--without-optimization' option

This follows mpv-player/mpv@b0ff0527a3.
add a vapoursynth formula

HEAD only because git master of VS builds on OSX
mpv: 0.4.2
mpv: add libdvdnav to dependencies
mpv: remove the dependency of libav

Homebrew's libav doesn't have any libraries because of
'--disable-shared'. Also, we don't think anyone uses it.