wmllint: remove -f --future option

Going back through wmllint's history, it turns out that there apparently
haven't been any "experimental conversions" since 1.4. Especially since
some new switches have been added recently, the clutter makes it no longer
worth keeping around.

A comment notes the option's disappearance, in case anyone is interested
in recreating experimental conversions again.

data/tools/wmllint

@@ -2666,7 +2666,6 @@ Other options:
                                applying to all sides.
     -s, --stripcr              Convert DOS-style CR/LF to Unix-style LF.
     -p, --progress             Names each file before processing (like -v -v).
-    -f, --future               Enable experimental WML conversions.
     -K, --known                Suppress check for unknown unit types, recruits,
                                races, scenarios, etc.
     -S, --nospellcheck         Suppress spellchecking
@@ -2679,11 +2678,10 @@ file itself.  See also: http://wiki.wesnoth.org/Maintenance_tools.
 
 if __name__ == '__main__':
     try:
-        (options, arguments) = getopt.getopt(sys.argv[1:], "cdDfhmnprsvKSZ", [
+        (options, arguments) = getopt.getopt(sys.argv[1:], "cdDhmnprsvKSZ", [
             "clean",
             "diffs",
             "dryrun",
-            "future",
             "help",
             "missing",
             "progress",
@@ -2694,6 +2692,7 @@ if __name__ == '__main__':
             "nospellcheck",
             "stringfreeze",
             ])
+        # -f --future has been removed; there have been no experimental conversions since 1.4
     except getopt.GetoptError:
         help()
         sys.stderr.write('\nAn option you have entered is invalid.  Review options and try again.')
@@ -2701,7 +2700,6 @@ if __name__ == '__main__':
     clean = False
     diffs = False
     dryrun = False
-    future = False
     missingside = True
     revert = False
     stringfreeze = False
@@ -2720,8 +2718,6 @@ if __name__ == '__main__':
             dryrun = True
         elif switch in ('-D', '--diffs'):
             diffs = True
-        elif switch in ('-f', '--future'):
-            future = True
         elif switch in ('-m', '--missing'):
             missingside = False
         elif switch in ('-p', '--progress'):