Google Maps V3 KeyDragZoom Utility

This package is a re-publication of the `KeyDragZoom` utility library for Google Maps JavaScript API V3, originally hosted on Google Code. Its primary function is to enable a 'drag zoom' feature on a Google Map, allowing users to draw a rectangle while holding a specified key (e.g., Shift, Ctrl) to zoom into that area. This utility fills a gap left by the discontinuation of Google Code hosting, which made the original `keydragzoom.js` resource inaccessible. The current stable version, 2.0.9, directly corresponds to the last official release from the original project. As a direct re-host, this package is effectively in maintenance mode with no active feature development or breaking changes since its original Google Code release; its main purpose is to ensure the utility remains available and installable via npm and Bower. It differentiates itself from core Google Maps functionality by providing a convenience layer for an advanced zoom interaction pattern not natively built into the basic API controls.