The code completion was keeping around references to old documents after
the completion finished. This caused documents to stay in memory when
unloading projects, up until the next time you used the completion.

ProjectExplorer::sessionManager -> ProjectExplorer::showSessionManager

Avoid creating a copy of the list of projects.

Conflicts:
	src/plugins/qt4projectmanager/qtversionmanager.cpp

Task:     -
RevBy:    -
AutoTest: -
Details:  Add the include path for qplatformdefs.h to the fot.

Task:     -
RevBy:    -
AutoTest: -
Details:  (Only outputs them via qDebug().)

Task:     -
RevBy:    -
AutoTest: -
Details:  Actually building only works on unix (since the generator is
hardcoded.) and make is called without any parameters which is wrong.
A lot is missing for basic build support, but this is a start.

RevBy:    Found by me.
(cherry picked from commit 58827feb)

Task:     - 234321
RevBy:    - Thorbjørn

Details:  Free the whole ProFile*, ProItem*, ProValue* and etc
structure after parsing, that frees around 200Mb for projects.pro.

The scope of the classes is now separated and displayed in the second
column, and not included in the search.

    enum ExtraSelectionKind {
        CurrentLineSelection,
        ParenthesesMatchingSelection,
        CodeWarningsSelection,
        CodeSemanticsSelection,
        OtherSelection,
        NExtraSelectionKinds
    };
    void setExtraSelections(ExtraSelectionKind kind, const QList<QTextEdit::ExtraSelection> &selections);
    QList<QTextEdit::ExtraSelection> extraSelections(ExtraSelectionKind kind) const;

This is mainly for the benefit of the cppmodelmanager.