Fix + format date/time values across entire site

-Added a new client-side library for date/time formatting: Luxon v1.26.0
-Added new date/time settings for display format, timezone (utc or local) and an option to enable alternate timezone tooltips
-All date/time values are now formatted via Luxon and displayed according to the new configurable settings
-All markets now return Trade History timestamp values as unix timestamp values formatted in seconds

settings.json.template

@@ -96,6 +96,21 @@
     //       NOTE: The path root is /public
     //             The optimum logo size is 128x128 as the image will be forced to 128px high when displayed
     "logo": "/img/logo.png",
+    // date_time: a collection of settings that pertain to the date and time values displayed in the explorer
+    "date_time": {
+      // display_format: The format to use when displaying date/time values
+      //                 Date/time values are formatted using the Luxon library and must follow the correct syntax (read more: https://moment.github.io/luxon/docs/manual/formatting.html#table-of-tokens)
+      //                 Ex: LLL dd, yyyy HH:mm:ss ZZZZ = May 27, 2019 22:04:11 UTC
+      "display_format": "LLL dd, yyyy HH:mm:ss ZZZZ",
+      // timezone: All dates and times are stored as UTC dates and can either be displayed in UTC format or else they can be displayed in the local timezone according to a user's web browser settings
+      //           valid options: utc or local
+      "timezone": "utc",
+      // enable_alt_timezone_tooltips: Determine if dates and times should have a mouse-over tooltip which displays an alternate timezone value
+      //                               If set to true and the "shared_pages.date_time.timezone" setting is set to "utc" then enabling this option will display date/time tooltips in the local browser's timezone
+      //                               If set to true and the "shared_pages.date_time.timezone" setting is set to "local" then enabling this option will display date/time tooltips in the UTC timezone
+      //                               If set to false, no tooltips will be displayed for any date/time values
+      "enable_alt_timezone_tooltips": false
+    },
     // table_header_bgcolor: Change the background color of all table headers
     //                       valid options: light, dark or leave blank ( "" ) for default colors
     "table_header_bgcolor": "",