[development] need a standard for contrib node build_mode constants

[Earl Miles]

Chris Johnson wrote:
> Maybe I'm missing something here, but it's just as possible to
> accidentally re-use a string constant as a numeric constant.  How does
> using a string help things at all?  Either the developer reads and
> enumerates a list of all existing uses and avoids collision -- or does
> not -- regardless of whether they are integers, strings, or ice cream
> flavors.
> 
> Please educate me!

Strings have meaning. Ints do not. Therefore if there is a collision it 
is at least a collision over meaning.