Safari / Firefox race condition

[strygo]

When the PinchZoom object is being initialized, an initial call to update() is scheduled. On Safari and Firefox, the IMG load event happens prior to the setTimeout, leading to the initial calls to establish offsets to be dropped.

• Resolve race condition by setting up offsets prior to setTimeout()
• Fix variable name typo
• include options object with addEventListener calls to resolve Chrome warnings

[sandstrom]

Thanks @strygo 💯