fix QSqlTableModel::headerData() for empty query with inserted row

QSqlQueryModel::headerData() relied on virtual indexInQuery() to
detect whether the requested column at row 0 mapped to an index in
the query. This failed when row 0 was a pending insert managed by
QSqlTableModel, and therefore not in the query.

The only thing that matters here is the column.

Task-number: QTBUG-29108
Change-Id: I3e0ae85ba223e444781ec8033386d394bb44f0e8
Reviewed-by: Andy Shaw <andy.shaw@digia.com>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
QSqlTableModel::setData(): fix non-change detection

Commit 10ff9de91bedf93852f13a58287afd8831644759 introduced the
optimization of ignoring non-changes, but it overshot the mark.
It neglected to consider that QVariant's equality operator does not
compare the null flag. It also failed to consider that setData() has
a useful side effect of setting the generated flag in a column of a
pending INSERT. This is important when the application actually wants
a NULL to be inserted into the column.

Task-number: QTBUG-29217
Change-Id: I1368f7acc21eebfeb5a8d23746fc38f6f30fd395
Reviewed-by: Andy Shaw <andy.shaw@digia.com>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
QSqlTableModel: support refreshing inserted rows with auto columns

Previously, selectRow() did not work after INSERTing a new row into a
table with an automatically populated column. It did not work because
the model did not know the primary values for the new row. Newly
inserted rows were therefore not refreshed in OnFieldChange and
OnRowChange edit strategies.

This change provides support for the typical simple case where a single
column is populated by the database and can be retrieved with
QSqlQuery::lastInsertId().

Task-Number: QTBUG-29102
Change-Id: Ibf0f0ac8661185bde57034ddf40c2178bece4778
Reviewed-by: Andy Shaw <andy.shaw@digia.com>
Reviewed-by: Lukas Geyer <lgeyer@gmx.at>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
Fixed crash in image reader when reading certain BMP files.

If the high bit in a mask is set, for instance if the mask is
0xff000000, and we shift it to the right by 24 positions, since the mask
was not declared as unsigned we ended up with a mask value of
0xffffffff. We then add 1 to this value and divide by the result,
causing a division by zero crash.

The masks need to be declared unsigned to prevent sign bit extension
when shifting right.

Task-number: QTBUG-29194
Change-Id: I79260344cebfbdd3ea86416a9c734dca76517999
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>