Cleaning up functions

[achafetz]

This package exports a ton of functions. I think we should make quite a few of them internal, so that the user isn't bombarded with functions and not clear what to use, eg datim_execute_query() or hierarchy_clean

[baboyma]

Sure. I personally used datim_execute_query() for testing / debugging other functions. Also used to design new queries.

Note: do not export these: hierarc.*_clean, rename, identify_ctry functions, these are used from pull_hierarchy()