[U-Boot] Handling of environment settings

Until now, custom environment settings were just defined in the board config file. All that had to be done is to edit the file, recompile the u-boot and flash it to the target.

Now, however, this approach is not longer acceptable. This means, that environment must be either set manually on the target or maintained and flashed as a separate blob, which is considerably less convenient.

So, two question here: 1. Is there a tool already which takes an environment description in some form and produces a flashable blob? 2. If not, is there some extra include file which is considered volatile and can hold user-defined environment settings?