DROP NOT NULL with DEFAULT

[mamonovd]

Drop both "NOT NULL" and "DEFAULT" on table column.
Switch order of parseDefinition patterns apply, otherwise column which has both "NOT NULL" and "DEFAULT" can't be modified to have none of them.

oldColumn: column_name column_type NOT NULL DEFAULT default_value
newColumn: column_name column_type
diff (v2.6.0): ALTER TABLE...
ALTER COLUMN column_name column_type,
ALTER COLUMN DROP DEFAULT;

but should be: ALTER TABLE...
ALTER COLUMN DROP NOT NULL,
ALTER COLUMN DROP DEFAULT;