Add map as a cue variable type

[brunchboy]

This will allow, for example, a dimmer oscillator cue to have the oscillator type be a cue variable; the map would have entries containing the four oscillator types, with keys being the name to present in the UI (both on the web and on the Push) when that option is selected. The web would use dropdown menus, the Push an overlay letting you scroll through the values. This would save a lot of space on the cue grid (and conceptually in show operators’ heads, perhaps).