Split the ecpg translation support into a separate catalog for the ecpg

Split the ecpg translation support into a separate catalog for the ecpg
preprocessor and the library.  This is useful for a number of reasons:

* The preprocessor and the library are in some cases installed in separate
packages and used by different classes of users.

* The library MO files need a different versioning scheme to account for the
soname.

* The makefiles are simpler, more robust, and easier to maintain this way.
(NLS web site was prone to break everytime a build rule changes.)

* Translators might choose to focus on the ecpglib, because that is more
user-facing.

* There was virtually no overlap, so nothing is lost.