MapToolIdentify moved to gui to make it accessible in python

app/QgsMapToolIdentify class has been separated in two:

gui/QgsMapToolIdentify for the generic identification process
app/QgsMapToolIdentifyAction for app specific (shows the dialog)

app/QgsIdentifyResults rename to app/QgsIdentifyResultsDialog

sip files added for QgsMapToolIdentify

The identify method can be called with parameters:
- Identify mode (default setting or active layer, or top-down, or stop at first)
- List of layers 
- Type of layer

A great thanks to Matthias Kuhn for his great support and advice.