Version number update for 5.1.23

Version number update for 5.1.22

Version number update for 5.1.21

Version number update for 5.1.20

Version number update for 5.1.19

Version number update for 5.1.18

Version number update for 5.1.17

Version number update for 5.1.16

Docs updates

Missing .tid extensions were causing those tiddlers to be mis-read.

Version number update for 5.1.14