Switch to dash encoding for table/database/row-pk in paths

* Dash encoding functions, tests and docs, refs #1439
* dash encoding is now like percent encoding but with dashes
* Use dash-encoding for row PKs and ?_next=, refs #1439
* Use dash encoding for table names, refs #1439
* Use dash encoding for database names, too, refs #1439

See also https://simonwillison.net/2022/Mar/5/dash-encoding/

tests/fixtures.py

@@ -406,6 +406,7 @@ CREATE TABLE compound_primary_key (
 );
 
 INSERT INTO compound_primary_key VALUES ('a', 'b', 'c');
+INSERT INTO compound_primary_key VALUES ('a/b', '.c-d', 'c');
 
 CREATE TABLE compound_three_primary_keys (
   pk1 varchar(30),