This reverts commit ebfcd35a.
Qt 4.5 commit b51dd5a7b328291c5dbda540ce228e7d867662cb eliminates the
need for this workaround for now.

Regression coming from the new navigation history mechanism.

page of its own now

The BaseTextEditor was unconditionally setting the mouse cursor on each
mouse move event, after which the CPPEditor would set it as well when
the mouse was above a link. This caused some mouse cursor flickering, so
now the cursor is only set when it's supposed to change.

Also fixed an issue where the link wasn't removed when leaving the text
editor with the mouse while Ctrl was pressed.

Task:     240811

Task:     240811

Task:     240811

Introduce setCodeFoldingSupported to the BaseTextEditor, and only
enabled it for the C++ and QtScript editors. This removes the useless
margin meant for code folding markers from the plain text editor and
.pro file editor.

This code is already in TextEditor::BaseTextEditor::openEditorAt.

Requested on the mailing list. Increases usability.

When the cursor isn't within the block that's being collapsed, it
shouldn't be moved. When it is, it will now move upwards instead of to
the start of the line.

Reviewed-by: mae

Many singletons have their own instance() method, in which case there is
no need to use ICore::instance() to get access to them.

replace ExtensionSystem::PluginManager::instance()->getObject<Core::ICore>() by Core::ICore::instance()

forward declaration is sufficient.

RevBy: Matthias

Pop it upwards when it would otherwise go below the screen and shift it
to the left when it would otherwise exit the screen on the right.

The mouse handling for code folding wasn't deactivated when the code
folding markers were hidden.

Reviewed-by: mae

in ifdefed out sections

when opening files from the C++ editor (e.g. when the user press F2 on #include <QMutex>).

support statements later.