0.9.2 - Better support for historical data & schema migrations

[tantaman]

I'm finishing up 0.9.2. This release will:

1. Allow you to convert tables, which already have data, to CRRs.
2. Allow you to add, remove and rename columns while preserving CRR metadata. Currently renaming a column does not carry over the metadata required to track the past values through merges.

You do need to run:

select crsql_alter_begin('crr_name');
... schema modification statements ...
select crsql_alter_commit('crr_name');

when migrating a CRR.

This brings us close to production readiness. Next missing piece is to prevent syncing between nodes that are on different schema versions.

The libsql port will remove the need for select stmt_with_sideffects