Decide on what functions should be exported

[seabbs]

As per the title we need to decide which functions should be exported (i.e. are designed to be used by a module user vs inside the module). We should also decide on a naming scheme for internal methods and check that all current code works as expected when these are not exported.

This issue was based on discussion in #40 where it was noted that several of the functions appeared to be for internal use only but were still being exported (i.e. we had a by default export all policy).