Fix dollar sign accessing of objects (like data frames), as pointed out by @frbrz (issue #16)
Use rxode2parse functions for internal event table
creation (where they were moved to).
Dropped C++14 and let the system decide.
Split off et(), eventTable() and
related functions.
Also split off rxStack() and
rxCbindStudyIndividual() in this package.
Added a NEWS.md file to track changes to the
package.