Remove 'valueAsNumber' property from observable list

The property was removed in a0bea641d1fcbec64caf6483c88c9ddb3bea814f
Change ol.dom.Input target param from Element to HTMLInputElement
Add missing function arguments
Listen to 'input' and 'change' events
Add opacity property to ol.style.Image
Handle image opacity in ol.render.canvas.ImageReplay
Handle image opacity in ol.render.canvas.Immediate
Set ol.style.Icon opacity
Merge pull request #1696 from fredj/ol.style.image-opacity

Add new opacity property to ol.style.Image
Merge pull request #1724 from fredj/ol.dom.input

ol.dom.Input cleanups
Remove Font Awesome

Everything that we need (icon-arrow-left, icon-arrow-right, icon-plus,
icon-minus, icon-download and icon-flag) is already provided by Bootstrap.
Make setValues consistent with repeated calls to set
Safer feature constructor

Calling setValues now behaves like calling set (closes #1672)
Merge pull request #1728 from tschaub/set-values

Make setValues behave like multiple calls to set.
Rename ol.Map#render to ol.Map#renderSync
Merge pull request #1727 from fredj/drop-fontawesome

Remove Font Awesome
Add an alternative algorithm for zoomify tier size calculation

Zoomify uses a different algorithm than ol3 to calculate the number of
tiles per tier.
These algorithms are compatible in most cases, but they will lead to
different results with some particular image sizes.

This update provides an option for the zoomify source to use one of
these two algorithms.
Fix handling of the color cache
Merge pull request #1730 from elemoine/colorcache

Fix handling of the color cache
Use shorter syntax for integer division by 2