Often we need to amend our schema, it is tempting to use
drop_table, rename_column and drop_column to amned schema
trouble though is that existing code that is running in production
can depend on the existance of previous schema leading to application
breaking until new code base is deployed.
The commit enforces new rules to ensure we can never drop tables or
columns in migrations and instead use Migration::ColumnDropper and
Migration::TableDropper to defer drop the db objects
This feature can be enabled by choosing a destination for the
`shared drafts category` site setting.
* Staff members can create shared drafts, choosing a destination
category for the topic when it is published.
* Shared Drafts can be viewed in their category, or above the
topic list for the destination category where it will end up.
* When the shared draft is ready, it can be published to the
appropriate category by clicking a button on the topic view.
* When published, Drafts change their timestamps to the current
time, and any edits to the original post are removed.
* Works with the current column layout exported as Excel file
* Tries to fix invalid CSV when it wasn't exported from Excel
* Imports categories
* Imports topics into the correct category
* Allows skipping archived topics
* Allows skipping private topics
* Makes use of the latest features from the base importer
* Some minor fixes and documentation updates
* Make sure the category description is imported correctly
(the about topic usually had the wrong excerpt).
* Allow import scripts to mark topics as closed or archived.
* Allow import scripts to store the topic's original id.
It will be stored in topic_custom_fields as import_topic_id.
