Support more items for QTextCharFormat::VerticalAlignment enum for custom text objects.

Support more items for QTextCharFormat::VerticalAlignment enum for custom text objects.

 * QTextCharFormat::AlignNormal - support text format descent, place text object bottom on (baseline - descent).
 * QTextCharFormat::AlignBottom - place text object bottom on baseline.
 * QTextCharFormat::AlignTop - Still not supported.
 * Any other vertical alignment is mapped QTextCharFormat::AlignBottom.

Add new enum AlignBaseline for custom inline objects to take into account font baseline.

Merge-request: 2578
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>
(cherry picked from commit ee9455ed2a83084692d969c398ecb91bcd4fc33a)