Small change to CLI; renaming file variables filename

-dailyfile becomes -dailyoutputfile
-peoplefile becomes -peopleoutputfile
-yearlypeoplefile becomes -yearlypeopleoutputfile

No other command line arguments should be affected, and the output should not change.

Internally, variables holding filenames are now called *Filename instead of *File.
*File is reserved for filehandles.  A handful of other trivial changes.  One error
message was corrected that referenced the wrong filename (minor bug).