Editor: Blockselection rewrite.

Also adding the possibility to insert text into the blockselection.

Task-number: QTCREATORBUG-7773
Change-Id: I7a47a1d630f769a8253ee1a2f21057820ea170d5
Reviewed-by: Lukas Holecek <hluk@email.cz>
Reviewed-by: Christian Stenger <christian.stenger@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/texteditor/codeassist/codeassistant.cpp

@@ -248,6 +248,9 @@ void CodeAssistantPrivate::requestProposal(AssistReason reason,
 {
     QTC_ASSERT(!isWaitingForProposal(), return);
 
+    if (m_textEditor->editorWidget()->hasBlockSelection())
+        return; // TODO
+
     if (!provider) {
         if (kind == Completion)
             provider = m_completionProvider;