Provide particle system number idempotence when loading and saving docs.

[ghost]

See in https://github.com/davewx7/citadel/commit/03206e8b8e3ae939d5d5267a8e998cc26bf5f546 how Argentum Age is incurring in unnecessary diff burden by not granting idempotence to decimals in its load and save document operations.

[ghost]

This is not actually affecting decimal numbers but (and not necessarily limited to) several classes relating particle systems, at least the Affector class, probably the Emitter class too.