improve parse_config in JSONSchema and SectionConfig

improve parse_config in JSONSchema and SectionConfig

The old code used string substitution for every line of the
input string, while perl can also iterate over all matches
via the /g re modifier, and can turn ^ and $ to act as
beginning/end of line via the /m modifier.

Effectively allowing a "match over all lines" via a simple
while ($data =~ /^.*$/gm);

The situation is a little different in SectionConfig because
there's a nested loop invovled which doesn't work with /g.
For this there are two options and I chose the safer one by
simply doing a split on newlines first.
The alternative would be to open the data as a
filehandle-to-string and use <$fh> to read lines, however
I'd have to throw in an eval{} to be sure to close the
handle afterwards.