[WIP] Performance improvements

[nvkelso]

• Set offset to array
• Always use same units in an array (like in offset)
• Add sizes on textures to for Tangram ES
• Simplify shield handling
• move JS functions to last filter eval
• Generally simplify layer filter setup
• Trust the server more for things like water areas
• Cleanup water waves shader (assigned to @tallytalwar)
• Cleanup other shader changes, including dots, etc (assigned to @tallytalwar)
• Other shader cleanups
• Better language filtering for country, region labnels
• Hillshade shader changes (not clear if necessary) - (@tallytalwar: no grave perf issues here)
• Dashes as style versus draw params for ferry, rail, steps (for Tangram ES) - (assigned to @tallytalwar, to make it work for ES) (f4192ac, 08aea82)
• lossless compress all textures (ef02ef3)
• Upgrade to Tangram JS v0.18
• Eye ball visual regressions

[nvkelso]

@tallytalwar Can you take a look at the shader errors here, please? Looks like it fails completely in Tangram JS v0.18 while partially fails in v0.16, from waves shader. There's also another one related to a shader color.

Tangram v0.16.1 [error]: Style: error compiling program for style 'dots-rev' (program key 'program') 
Tangram v0.16.1 [error]: Style: error compiling program for style 'dots-rev-grid' (program key 'program') 
Tangram v0.16.1 [error]: Style: error compiling program for style 'horizontal-bars' (program key 'program') 
Tangram v0.16.1 [error]: Style: error compiling program for style 'waves' (program key 'program') 

[tallytalwar]

@nvkelso Sure, assigned myself to a few things in the description above.

[tallytalwar]

Savings from lossless compressions.

[tallytalwar]

@nvkelso over to you now.

[nvkelso]

For the waves shader, I like how the position is constant now, but can we do something similar to the landuse dots in Bubble Wrap dots – where the waves size is more "constant" looking for the 2 major waves, but the new wave that's introduced grows from a pixel to a full line width wave during the zoom?

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[nvkelso]

From @meetar, about the wave pattern:

My 2¢: I'd suggest eventually switching to a texture, and crossfading between zooms, as in the current map. I have an example using Tangram here: http://tangrams.github.io/texture-demos/?url=scenes/texture-tiles.yaml

[tallytalwar]

Cross fade for texture is good, but I think we can have a pure mathematical implementation for desired wave transitions.