#38 Nansat.reproject() creates self.vrt.vrt; VRT.copy() copies also VRT.vrt; test_vrt.py shows how it works
#38 add Nansat.undo() docstring
#38 add Nansat.undo() and VRT.undo() for restoring subVRT
#38 add VRT.get_sub_vrt() - iterative undo
#38 add VRT.get_spawner_vrt
#38 change Nansat.resize to fit new concept
#38 merge resize and resize_lite in Nansat
#38-new-vrt fixed bug in Nansat.resize of projected images: geotransform is also modified according to resize
#43 adding method Nansat.crop
#38 vrt.copy() copies adsVRT as well.
#43 nansat-crop modify SrcRect and DstRect
#38 vrt.copy() copies all attributes whose name starts with 'sub_'. Modify mappers which has vrt attributes.
#38 all subVRTs are in vrt.subVRTs dictionary.
#48 #51 VRT.get_super_vrt remove PixelFunction from Metadata, Nansat.crop add news GCPs, Domain._tranform_points moved to VRT.transfrom_points, Domain._get_rpojection moved to VRT.get_projection; croping and resize works for RS2
Merge branch 'issue43-nansat-crop' into issue38
#38 Nansat.add_band: add new super VRT and add band to this supVRT
#38 fix docstrings, fix some bugs related to VRT.get_projection, restore VRT.get_resized_vrt, move vrt and subVRTs from __init__ to class VRT, adding examples
#51 #43 use interactive PointBrowser for electing extent of the crop
#51 #43 add lonlim, latlim to Nansat.crop
#38 fixing bug in VRT.get_shifted_vrt which returns ill formed XML