updates to virtualrasters.py

https://github.com/pyinstaller/pyinstaller/wiki/Recipe-Multiprocessing

fixed map rendering error: changes in mapview & sensor specific render settings will be applied also on non-visible QgsMapCanvases

utils.py refactoring (loadUi -> loadUI, affects many widget classes)

added cursorlocationvalue.py + panel
added spectrallibraries.py + panel
added a couple of new icons
added trees.py (basic TreeModel system)

TimeSeriesViewer inherits QgisInterface
refactoring maptools
 - added mapcanvas.MapTools
 - TimeSeriesviewer.onShowProfile handles location based maptool requests (CursorLocation, Temproal/spectral prpofiles)

fixed bug in mapvisualization.py

MapCanvas: used MapCanvasLayerModel that support lazy loading of QgsMapLayer instances
MapViews can have individual vector layer sources for overlay

minor changes

several updates to mapvisualization.py
cleanups + refactoring

fixed icon of mainwindow

mapvisualization: fixed several optical issues, connected buttons

changen MapViewUI layout form horizontal to vertical
added MapView specific crosshairs

first steps to change MapViewCollection UI