New code assist API

This is a re-work of our completion engine. Primary goals are:

- Allow the computation to run in a separate thread so the GUI is not locked.
- Support a model-based approach. QStrings are still needed (filtering, etc), but
internal structures are free to use more efficient representations.
- Unifiy all kinds of *assist* into a more reusable and extensible framework.
- Remove unnecessary dependencies on the text editor so we have more generic
and easily "plugable" components (still things to be resolved).

src/plugins/texteditor/codeassist/iassistprocessor.cpp

@@ -0,0 +1,61 @@
+/**************************************************************************
+**
+** This file is part of Qt Creator
+**
+** Copyright (c) 2011 Nokia Corporation and/or its subsidiary(-ies).
+**
+** Contact: Nokia Corporation (info@qt.nokia.com)
+**
+**
+** GNU Lesser General Public License Usage
+**
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this file.
+** Please review the following information to ensure the GNU Lesser General
+** Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** Other Usage
+**
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at info@qt.nokia.com.
+**
+**************************************************************************/
+
+#include "iassistprocessor.h"
+
+using namespace TextEditor;
+
+/*!
+    \class IAssistProcessor
+    \brief The IAssistProcessor is an interface that actually computes an assist proposal.
+
+    \sa IAssistProposal, IAssistProvider
+*/
+
+IAssistProcessor::IAssistProcessor()
+{}
+
+IAssistProcessor::~IAssistProcessor()
+{}
+
+/*!
+    \fn IAssistProposal *perform(const IAssistInterface *interface)
+
+    Computes a proposal and returns it. Access to the document is made through the \a interface.
+    If this is an asynchronous processor the \a interface will be detached.
+
+    The processor takes ownership of the interface. Also, one should be careful in the case of
+    sharing data across asynchronous processors since there might be more than one instance of
+    them computing a proposal at a particular time.
+
+    \sa IAssistInterface::detach()
+*/