nicer names for functions that handle internal data structures

[Licenser]

Followup on #71 to keep track. The idea was that a suffix of 1 to indicate a function handles internal data structures comes with the problem that it is less then obvious without knowledge of the code. Changing this would be a api breaking change so only sensible with during a major version change. Alternatives suggested in the original issue were:

• _i, _internal, _r or _raw as suffixes
• a separate module while keeping function names identical

[jchassoul]

Hi Robert, wondering if you have new thoughts about this internal and external API, it's something that will break things... but it will make all more comprehensible in general and probably help even some new space adventurers! (=