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)

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

mapvisualization: fixed several optical issues, connected buttons

changen MapViewUI layout form horizontal to vertical
added MapView specific crosshairs

added __main__.py (in progress)
added option to load center pixel automatically

added # -*- coding: uft-8 -*-   and  # noinspection PyPep8Naming to each module
added GPL License statement to each module
added from __future__ import absolute_import to each module

moved loadUIFormClass(jp(DIR_UI, p)) to utils.py and (yessss!) removed an error occurred with newline character in *.ui inline HTML

MapCanvas.setRenderer(renderer) handles QgsRasterRenderer and QgsFeaturerRendererV2

- new context menu actions, e.g. set stretch to current area
- stretchToExtent(self, spatialExtent, stretchType='linear_minmax', **stretchArgs)
  to support different stretch types
- lazy loading of new data sources,

refactoring

MapCanvas accesses STV directly
Setter functions take care on none-updates

less chained pyqtSignals -> MapCanvas accesses parent SpatialTemporalVisualization, MapView, etc. instances directly

cleanup, refactoring,smaller fixes

toggle crosshair visibility for for all mapviews, selected mapviees, single map canvases

added logging
TsvMapCanvas.setshowCrosshair + context menu actions related to this