This checkin removed configgetEditableColorSpace(...). Users should
use the existing getColorSpace, and addColorSpace as replacements.

getEditableColorSpace has always been a wart on the OCIO API, as this
is the only function that lets you manipulate the contents of a
configuration behind its back (not using a "set" calls). Removing
this function now lets us perform internal caching with 100%, where
all changes (such as addColorSpace) will clear caches as appropriate.

Commits:
03301d29018

-- Jeremy