The image loading done in Preload.js used an array to store
image src and image object as 2 consecutive entries in that
array. Using the src as an index in a hash allows direct
instead of a linear search and also allows to store more data.
* improved cleanup of images loaded with the proxy
* this also adds a timeout for the image loading phase, after that
running image requests are aborted and the rendering is started
* normally when exporting jpeg any pixel that was transparent
becomes black, make them white
* check for window.console.log before use (avoid crash)
* html2canvas.Parse: fix missing call to html2canvas.Util.Extend for the
given options
* read the version from version.txt
* set default target to build
* added dependencies to all targets
* allow the build to run without a local copy of the closure compiler
* updated license header with @VERSION@ which will be replaced during the build
* added the license header to all files (that one will be stripped out by the closure compiler)
