fixed speclib import error

updates to virtualrasters.py

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)

first steps to change MapViewCollection UI

virtualrasters.py - fixed setData(<vrt band name>)

removed frame lines from GUI

added new Icons

virtualrasters.py : added feature identify to preview map

added several functions to virtualrasters.py: CRs handling, internal CRS warping (VRT based), bound handling,...

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

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

VirtualRasterBuilder: added removeVirtualBands(), addVirtualBand(), insertVirtualBand(), addFilesAsStack(), addFilesAsMosaic(), improvements to saveVRT()