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/Starting/Part3/Tutorial-for-basic-MUSH-like-game.md

@@ -150,7 +150,7 @@ class CmdSetPower(Command):
             return
         # at this point the argument is tested as valid. Let's set it.
         self.caller.db.power = power
-        self.caller.msg("Your Power was set to %i." % power)
+        self.caller.msg(f"Your Power was set to {power}.")
 ```
 This is a pretty straightforward command. We do some error checking, then set the power on ourself.
 We use a `help_category` of "mush" for all our commands, just so they are easy to find and separate
@@ -295,11 +295,17 @@ class CmdAttack(Command):
         caller.db.combat_score = combat_score
 
         # announce
-        message = "%s +attack%s with a combat score of %s!"
-        caller.msg(message % ("You", "", combat_score))
-        caller.location.msg_contents(message %
-                                     (caller.key, "s", combat_score),
-                                     exclude=caller)
+        message_template = "{attacker} +attack{s} with a combat score of {c_score}!"
+        caller.msg(message_template.format(
+            attacker="You",
+            s="",
+            c_score=combat_score,
+        ))
+        caller.location.msg_contents(message_template.format(
+            attacker=caller.key,
+            s="s",
+            c_score=combat_score,
+        ), exclude=caller)
 ```
 
 What we do here is simply to generate a "combat score" using Python's inbuilt `random.randint()`
@@ -359,7 +365,7 @@ class Character(DefaultCharacter):
         looker sees when looking at this object.
         """
         text = super().return_appearance(looker)
-        cscore = " (combat score: %s)" % self.db.combat_score
+        cscore = f" (combat score: {self.db.combat_score})"
         if "\n" in text:
             # text is multi-line, add score after first line
             first_line, rest = text.split("\n", 1)
@@ -435,12 +441,17 @@ class CmdCreateNPC(Command):
         npc = create_object("characters.Character",
                       key=name,
                       location=caller.location,
-                      locks="edit:id(%i) and perm(Builders);call:false()" % caller.id)
+                      locks=f"edit:id({caller.id}) and perm(Builders);call:false()")
         # announce
-        message = "%s created the NPC '%s'."
-        caller.msg(message % ("You", name))
-        caller.location.msg_contents(message % (caller.key, name),
-                                                exclude=caller)
+        message_template = "{creator} created the NPC '{npc}'."
+        caller.msg(message_template.format(
+            creator="You",
+            npc=name,
+        ))
+        caller.location.msg_contents(message_template.format(
+            creator=caller.key,
+            npt=name,
+        ), exclude=caller)
 ```
 Here we define a `+createnpc` (`+createNPC` works too) that is callable by everyone *not* having the
 `nonpcs` "[permission](../../../Components/Locks#Permissions)" (in Evennia, a "permission" can just as well be used to
@@ -532,10 +543,10 @@ class CmdEditNPC(Command):
             return
         if not self.propname:
             # this means we just list the values
-            output = "Properties of %s:" % npc.key
+            output = f"Properties of {npc.key}:"
             for propname in allowed_propnames:
                 propvalue = npc.attributes.get(propname, default="N/A")
-                output += "\n %s = %s" % (propname, propvalue)
+                output += f"\n {propname} = {propvalue}"
             caller.msg(output)
         elif self.propname not in allowed_propnames:
             caller.msg("You may only change %s." %
@@ -619,7 +630,7 @@ class CmdNPC(Command):
             return
         # send the command order
         npc.execute_cmd(self.cmdname)
-        caller.msg("You told %s to do '%s'." % (npc.key, self.cmdname))
+        caller.msg(f"You told {npc.key} to do '{self.cmdname}'.")
 ```
 
 Note that if you give an erroneous command, you will not see any error message, since that error