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)

virtualrasters.py : added feature identify to preview map

added classificationscheme.py
utils.py added value2str
added vrtbuilder.ui
virtualrasters: multiple changes (in progress) related to vrtbuilder.ui

refactoring

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

SensorPlotStyle get restored
PixelLoader.py: CRS transformation in pure GDAL due to problems with QgsCoordinateTransformation in non-main thread
utils.geo2px() now casts geo2pxF coordinates to integer (instead of rounding them)

utils.py added loadIcon()
mapvisualization.py implemented MapCanvas loading activity bar

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

added sigShowVectorOverlay and sigRemoveVectorOverlay

added niceNumberString(number) to get human readable number strings

MapCanvases get registered at responsible Controllers (STV, MV and DV)
utils.saveTransform(geom, crs1, crs2) takes care on invalid coordinate transformations

renamed fileSizeString to scaledUnitString

cleanup, refactoring,smaller fixes

added logging
added fileSizeString(num)
added SpatialPoint(QgsPoint)
added filterSubLayers(filePaths, subLayerEndings) and getSubLayerEndings(files)