Include Cont. Ed. courses in XML4 output

The predicates for the XML4 template, offering, and section list
functions do not cover Continuing Education. Include courses for output
when code_info.system is “Destiny One”.

Fixes #6.
Accommodate course section codes from Destiny One

Destiny One provides course codes with _SEC appended in enrolment
files. Remove the end of line token from the regular expression test
for Continuing Education courses to accommodate this.

Fixes #7.