refactor disconnectFromFtp to remove cached entries when necessary

In cases where a cached ftp connection fails to connect, or a file
transfer has failed, we should removed the cached connection. Since qnam
has an idea of a single internal QFtp per full operation, when file
transfers failed previously the cached connection would be reused for
subsequent connections and thus fail.

[ChangeLog][QtNetwork][QNetworkAccessManager] QNetworkAccessManager now
properly handles FTP transfer failures by removing failed cached ftp
connections.

Task-number: QTBUG-40797
(cherry picked and adapted from qtbase/45cbbe56bc13216b83215ea148590eccf81f420a)
Change-Id: Ie9eec5ec54af16a8d19e34d04bdd993cc7bbd0f5
Reviewed-by: Richard J. Moore <rich@kde.org>
Mac Style: Fix QLineEdit frame in 10.10

Also removes some dead code.

Backport of 83f06da1c6bffff61af78cbe75a0691d53742b53 from qt5/qtbase

Change-Id: I7e088ca8b52bc3e2da25e29ab570469eab6f97bf
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>
QMacStyle: Fix focus frame rendering in Yosemite

Using the HITheme API would result in the frame's right edge
to be missing.

Instead, we use the recommended technique to draw the focus
ring around a custom NSCell. (See
https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ControlCell/Articles/ManipulateCellControl.html)

Backport of 769af6689337285927a2637b184149f688332542 from Qt5/qtbase

Change-Id: I8f3992edc065e14632ec4e473732b30bcf4c1937
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>