(this is a tool just for the ntppool system ...)

- Travis update to latest two revisions (1.16.9, 1.17.2)
- Drone update to latest Go revision (1.17.2)
- Alpine docker update from 1.14-3.11 --> 1.17-3.14

Add goroutine to watch file modification time each minute. Lock and
update the files independently if the modification time is newer than
the last time it was loaded.

Also ancillary fixes for type signatures, and formatting test files.

Fixes #116, #16

bug: read lock missing from GetLocation

GetLocation operates on a *geoip2.City (pointer) but does not incur a
read-lock on the GeoIP struct like other functions.

- Remove default execution in the for-select loop with the watchFiles
  ticker (per feedback in PR #128)
- Migrate the DB-reload code into its own function to cleanly use the
  defer-unlock pattern (also per feedback in #128)

Per feedback in PR #424, change functions `open`, `New`, and the GeoIP2
struct to allow for independent lock management, update the file in-place if
`open` is called again, and remove enums and other references in the
package.

Add checks for the DB to be active before making a query. This was only
enabled on ASN, now enabled for City and Country queries.