This pull requests replaces type check hint assertions with type casts,
library sanity check assertions with conditional console.assert statements
in debug mode, and runtime sanity checks with assertions that throw an
ol.AssertionError with an error code for lookup outside the library.
If ol3 is included as part of a concatenated build and the script before it does
not end in a semi-colon, the IIFE is interpreted incorrectly (often resulting in
`TypeError: (intermediate value)`).
When concatenating the Closure Library, base.js creates a new `goog` object if there is not already one in scope. Later, `goog.global` is assigned the value of `this`. Calls to `goog.provide` create "namespace" objects by assigning to `goog.global`. To ensure that `goog` is the same as `goog.global.goog`, we need to create a new `goog` object in the scope of base.js and assign it to `this.goog`.
This reworks the changes in #2442 so we always include the version info, regardless of whether the module is run as main or not. This also addresses a few lint related issues.
By default, all paths in the build config (e.g. externs) are assumed to be relative to the ol3 repo root. To make it so relative paths are resolved from a different directory, use the cwd option.
In addition, this change makes it so the `build.js` task can be run from another directory.
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.
