Add drop, sort commands, start tail command; implement support for destructuredOrLines match type; misc fixes

HELP.txt

@@ -109,6 +109,9 @@ on <line|word> <index> <command...>
     Run the given command on the nth line or word.
     Example: on line 2 prefix +
 
+drop <line|word|index> <index>
+    Drops the nth line, word, or element from the subject.
+
 map <line|word> <start index> [to <end index>] [by <nth lines>] <command...>
     Map the subject line-wise or word-wise for the given range.
     Default is to map until the end of the string if `to` is not provided,