In the Edit Table dialog we used to call our alterTable function (which
works around SQLite's missing full ALTER TABLE support by - besided
other things - copying all the data of the table) for pretty much every
change immediately. This was taking a lot of time for larger tables.
Our alterTable function allowed any number of changes if they affect
only one field of the table at once. So we could have reduced the number
of calls a lot by just using that capability. Instead however, this
commit improves the alterTable function to make possible transforming a
table completely in just one call. It does so by taking the new table
schema and using that without further modification. It also takes a new
parameter to keep track of what column in the old table becomes what
column in the new table, so the data can be preserved.
This commit obviously also changes the Edit Table dialog to make proper
use of the new features. This means that whatever changes you make to a
table, you will only have to wait once until for the alterTable call,
and that's when clicking the OK button.
See issue #1444.
