introduced SensorTableModel to show sensors in QTableView
introduced TsvMimeDataUtils to extract information from QMimeData objects
renamed MapViewManager to SpatialTemporalVisualization
introduced TimeSeriesDatumView -> represents a column in SpatialTemporalVisualization
introduced TimeSeriesDateViewCollection
introduced MapViewCollection
TimeSeriesTableModel: sorting, some helper functions
MapView: sigSensorRendererChanged, MapView.sigSpatialExtentChanged

added activateMapTool(mapToolKey)  to TimeSeriesDatumViewManager and TimeSeriesDatumView

refactoring (a lot), minor cosmetics

minor UI changes

action based event handling

simplified labeling: uses now mouse buttons to add / remove observation dates from the date collection

recognizes observation date from Landsat scene ID in file names

ImageChip context menu offers:
- to load the respective scene in QGIS
- to copy the image chip to the clipboard

changed BandView widgets

new capabilities:
save and load text file based definitions of time series data files
supports multiple sensors in a time series