Toggle bike interlay with 'visible' flag instead of filters

[matteblair]

@nvkelso @sensescape The visible layer flag seems to do what you are trying to achieve by querying global flags in filter functions. Using visible is more efficient for the engine and (in my opinion) reads more naturally.

I believe this changes preserves the previous behavior, but I haven't been looking at this scene as long as either of you.

[nvkelso]

I'll have a look...

[nvkelso]

I think there's a path forward here (to use more visible properties rather than always filter options), but the current PR ends up showing bike map stuff by default (oops), and removes most minor roads (by default, but restored in bike mode?!). I'll have a closer look tomorrow.

[matteblair]

Whoa, that is not at all what happens in tangram-es. This definitely deserves a closer look!

[matteblair]

@bcamper and I were puzzling through this and we discovered that the primary reason this change behaves differently on JS and ES is that the two engines have different interpretations of the layer visible flag.

In tangram-es if a layer has visible: false, that layer and its sublayers will not be visible, regardless of any visible flags in the sublayers.

In tangram-js if a layer has visible: false, that layer and its sublayers will not be visible unless a sublayer has visible: true.

The syntax documentation doesn't specify one way or the other: https://mapzen.com/documentation/tangram/layers/#visible, so before going any further with this PR, we should standardize this behavior.

[nvkelso]

Once Tangram JS v0.12 lands I'll refresh this PR...

[nvkelso]

JS and ES now support enabled, I'll have another look at this soon.

[nvkelso]

Fixed in https://github.com/tangrams/walkabout-style/pull/165/commits/82e4c860b0439e1e46d165ae4024134598cae889 via the other PR. Closing this one.