begin clearing errors and warning

[u-an-i]

80 % type-based: <Qxxx> added, Qt:: added, Qyyy::ENUM changed, QVector overlaods deleted (is alias of QList), QzzzLiteral are now simply QzzzString, QFileInfo constructor around paths, comparison with letters: 'A' (not "A"), some new methods ("secsSinceEpoch" instead of "time_t", "setEncoding" instead of "setCodec", ... some explicit casts (5%) some msvc #pragmas (5%) logic adjusment File Dialog (3%), logic correction SQL (7%) (prepared statement placeholders have no API to get them!)

[u-an-i]

For reference:

[albar965]

Not sure if I want to go the Qt 6 path. Looks like a lot of effort and I expect plenty of side effects. I even don't want to know what the dock window management is doing now. :slightly_frowning_face:

[u-an-i]

i leave this PR here in draft state not continuing the upgrade for now.

[albar965]

Let's keep this in mind for a future version. Maybe after 2.8.