Stay on the world when transforming coords.

Instead of a transform that results in +/- Infinity northing, we can constrain the results to be within the world bounds.
Move zeroPad function to BaseTypes and add tests for it
Modify classes which contained an internal numeric zero padding function to use the one in BaseTypes instead
[New] raise feature function to move features in layer.
Image loading performance improvements

Performance improvements are achieved by using requestAnimationFrame when
a tile's visibility changes, and by not starting with a blank image when
creating a new tile image. It seems that even Firefox does not show a
loading placeholder when the tile is made visible in an animation.
Prevent KeyboardDefaults.js from triggering keyboard events when user is typing into the form elements for IE
use OpenLayers.Event.element
Absolute calculation of tile bounds

This avoids cumulated tile bounds errors for layer types that do not use a
tile row/column index in requests (e.g. WMS).
No deltas for tile bounds/position calculation

Now we also do not use deltas for shiftRow and shiftColumn. Some
refactoring was done so we do not need different calculateGridLayout
methods for layers with top-left and bottom-left tile origin.

TODO: With this commit, ArcGisCache and KaMap layers are broken.
Fixing ArcGISCache layer

This is done by caching the tileOrigin at grid creation time.
Fixing KaMap layer

This also fixes an issue that has gone unnoticed for a while: the grid did
not cover the bottom of the map viewport, but instead covered an invisible
area above the top of the map viewport.
Removing console.log line
Better precision for right and top corners
Optimizing positions for rendering

Calculating pixel positions from origin and grid index causes alignment
issues in the grid. By going back to incremental positioning, we get a
result without blank spaces between tiles again.
Register application listener after the control's
Do not cache data from aborted tile loads

This also results in a simplified cache method that can more easily be
overridden for use with other storage providers.
Fixing typo
Camel casing method name
Merge pull request #634 from ahocevar/634

CacheWrite caches an empty image if the tile is unloaded before the image is loaded. r=@bartvde
Updating and fixing API docs