As decided at yesterday DMLT meeting the time-critical part of the PPDB is to be called APDB and we should also rename all related things to be consistent with that name change. Fortunately there is not many packages that have `ppdb` in their name (just one) and there seem to be just few dependencies and they all need to be updated to. Here is what quick github search shows for packages that import dax.ppdb:

• ap_association, ap_pipe – our main customers
• verify
• lsst-dm/ap_pipe-notebooks
• lsst-dm/l1dbproto – this is my own code used for prototyping
• DMTN-113 and DMTN-098

In some instances ppdb appears not only as the reference to the imported dax.ppdb package but also in the names of the applications, modules, or public classes, e.g. lsst/ap/pipe/make_ppdb.py

The proposal for how to rename all these is:

• dax_ppdb is naturally renamed to dax_apdb.
• In dax_apdb all modules/classes with ppdb in the name are renamed.
• In all dependent packages imports of lsst.dax.ppdb renamed to lsst.dax.apdb
• In all dependent packages modules and classes that have ppdb in the name are renamed too.
• I'm going to update lsst-dm/l1dbproto myself but will not touch lsst-dm/ap_pipe-notebooks as I guess it contains notebooks and that needs to be tested in Jupyter.
• DMTNs will not be changed for now. 

P.S. I expect the new name (APDB) will cause much confusion, if pronounced "correctly" it will be confused with "a pdb" (with obvious question how Python debugger helps here?) I think less confusing way to say it is like "ape db", so this is what I'm going to practice.