qml: solve race condition when deleting while indexing

Task-number: QTCREATORBUG-10734

Change-Id: I521ac0881ff83a44846b133de5c292af8cda9d4e
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
qmljs: use QTC_OVERRIDE in qmljsmodelmanager

Change-Id: I3cf1c241a236f8b38fda1b4d40c45e75faa3a1f7
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
Doc: add info about Imports tab in Library

Update the screenshot.

Change-Id: Ief6eaf0617a31abdd07e186a8e90224920a02864
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
Doc: update buttons topics

Update changed field names, remove information about
an obsolete field, and make terminology more consistent.

Change-Id: I71cde2f371de5dc6e04658cc052601994fbf2aad
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>