[feat] nicer icons for mac (higher res, black lines)

icon/18_blocked_unix.go

icon/18_off_unix.go

icon/18_on_unix.go

icon/18_wait_0_unix.go

icon/18_wait_1_unix.go

icon/18_wait_2_unix.go

icon/18_wait_3_unix.go

icon/Makefile

icon/blocked_darwin.go

icon/blocked_unix.go

icon/off_darwin.go

icon/off_unix.go

icon/on_darwin.go

icon/on_unix.go

icon/png/18/vpn_blocked.png

icon/png/18/vpn_off.png

icon/png/18/vpn_on.png

icon/png/18/vpn_wait_0.png

icon/png/18/vpn_wait_1.png

icon/png/18/vpn_wait_2.png