saga_gui, map drawing: background color, transparency issues
pj_proj4/crs_transform_grid.cpp: parallelization disabled, bcos proj4 functions seem not to be completely thread safe (workaround might follow)
saga version updated to 2.2.0
replace outdated changelog with short text note where to find recent changelogs and other release information
shapes_lines: new tool 'Line Smoothing' (by iterative averaging) implemented
Transform Shapes: extend module to allow 3D shapefile processing
saga_api, grid system, bug fix: correctly invalidate grid systems - invalid grid systems are identified by a cell size of -1, so do not set it to zero erroneously (otherwise Grid_System->is_Valid() returns true for broken systems)