Add attributions example

Showing how to dynamically change collapsed/collapsible properties for ≠
map sizes.
Remove reference to ol-logo
Use @api annotation
Merge pull request #2159 from tonio/attributions

Merge Logo control into Attribution
Be stricter with the type of ol.source.TileWMS#_urls
Add tilePixelRatio option to ol.source.XYZ
Add ol.source.TileWMS#setUrls and setUrl
Merge pull request #2335 from elemoine/pixelratio-xyz

Add tilePixelRatio option to ol.source.XYZ
Merge pull request #2336 from elemoine/seturl

Add ol.source.TileWMS#setUrls and setUrl
Add maxZoom to ol.View.fitGeometry() options
Merge pull request #2340 from tsauerwein/view-fitGeometry-maxZoom

Add maxZoom to ol.View.fitGeometry() options
Remove static and other attributes from the docs
Minify CSS
To force a download by setting the href, we need synchronous rendering
Merge pull request #2347 from tschaub/render-sync

Fix the export map example.
Improve docs for projection
Expand on docs for observable properties
Merge pull request #2350 from probins/obj

Expand on docs for observable properties
Merge pull request #2346 from tschaub/clean-css

Minify CSS.
Always regenerate info using all sources if any have changed

Because we don't know if a new or modified file includes changes to the class hierarchy, we regenerate info for all sources any time any one has changed.  An alternative would be to generate info first for the new or modified file and then (potentially) regenerate info for more source files in the class hierarchy, but this makes the generate-info.js task far more complicated.