issue #2243 -- prefer f-strings over %-interpolation

edited docs to prefer f-strings, then str.format(), and remove %-interpolation

additional ad-hoc documentation fixes, as opportunities seen:
- replace Built-In Function (BIF) "min" variable with "mins"
- prefer BIF str(var) over "%s" % var
- reformat some code examples to clarify multiple args passed to functions
- change some single-quote strings to double-quotes for consistency
- fix mismatched parens

misc edits:
- add .vscode/ to gitignore

docs/source/Howto/Gametime-Tutorial.md

@@ -252,11 +252,10 @@ class CmdTime(Command):
     def func(self):
         """Execute the time command."""
         # Get the absolute game time
-        year, month, day, hour, min, sec = custom_gametime.custom_gametime(absolute=True)
-        string = "We are in year {year}, day {day}, month {month}."
-        string += "\nIt's {hour:02}:{min:02}:{sec:02}."
-        self.msg(string.format(year=year, month=month, day=day,
-                hour=hour, min=min, sec=sec))
+        year, month, day, hour, mins, secs = custom_gametime.custom_gametime(absolute=True)
+        time_string = f"We are in year {year}, day {day}, month {month}."
+        time_string += f"\nIt's {hour:02}:{mins:02}:{secs:02}."
+        self.msg(time_string)
 ```
 
 Don't forget to add it in your CharacterCmdSet to see this command: