Task-number: 233285

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.

Reviewed-by: hjk

By avoiding searching for the definition when it isn't necessary.

Cause blue doesn't fit nicely in all color schemes.

People with KDE 4.2.0 please update to 4.2.1 ...

Reviewed-by: dt

Reviewed-by: dt <qtc-committer@nokia.com>
 enter the commit message for your changes. Lines starting

There's no place to jump to in these cases.

Allowed customizing the link for includes and macro uses and fix it for
highlighting the name.

Allows navigating the code using the mouse when pressing Ctrl. Suggested
a few times and also seen in other IDEs.

Reviewed-by: hjk

Reviewed-by: dt