Release v0.019

This release fixes a few bugs and inconsistencies in the ysql command, in anticipation of a blog post explaining how it works.

We removed the "write" command in favor of making the "query" command accept input on STDIN and handle placeholders. So now you can run "SELECT" queries for each document as it comes in, perhaps to look up users as something else write's YAML with their ID in it.

Full changelog below:

• add missing ABSTRACTs to Command modules
• add error checking when preparing or executing SQL (#92)
• allow using "--dsn" to edit config (#91)
• combine write and query in ysql
• fix test failure on DBD::SQLite 1.33 (#86)