DBBrowserDB: Attempt to restore views, indices etc. in renameColumn()

Save views, triggers and indices before deleting the old table in
renameColumn() and try to create them again after renaming the new
table. This is likely to fail and we'd probably need a grammar for these
objects to make the appropriate changes, so in case it does fail this
just prints a warning with some ideas of what to do.
EditTableDialog: Warn when trying to set AI flag on non-integer column

Show a warning and abort the action when trying to set the auto increment
flag on a column with non-integer values in it because SQLite doesn't
allow setting the flag on these columns.
DBBrowserDB: Clean up logSQL() method
DBBrowserDB: Use SQL grammar for getting fields of table

When reading in the DB layout use our SQL grammar parser to determine
the fields of a table. This simplifies the code a bit and might also
give more detailed information in some situations.
DBBrowserDB: Merge renameColumn() and dropColumn()

Merge the renameColumn() and dropColumn() methods. They are just way too
long and complicated but also very similar that it makes no sense to
keep them separated.
This also simplifies the code of renameColumn() a bit while fixing the
trigger/view/index problem in dropColumn().