This allows users to build ol3 without anything exposed in the
global namespace. This can e.g. be useful for creating an ol3
AMD module, by simply using a build configuration with
"define('ol',function(){var o={};%output%return o.ol;});" as
"output_wrapper".
Whitespace builds are still painful to debug. Skipping the compiler altogether and simply concatenating sources is a better option for development and debugging. By ommitting the `compile` option in a build config, the output is "uncompiled" - a straight concatenation of all sources in dependency order.
