wxGUI: Add support for grass.pygrass API to Graphical Modeler

[landam]

Currently the Graphical Modeler is using GRASS script API (grass.script.core.run_command()) when converting model into Python code. This cannot be changed by the user.

This PR adds support for PyGRASS API (grass.pygrass.modules.Module). GRASS script package is still default. This can be changed in the settings.

Compare sample model:

1. GRASS script package (default):

from grass.script import run_command
...
    run_command("v.rast.stats",
                flags='c',
                map="zipcodes_wake",
                layer="1",
                type="point,line,boundary,centroid,area",
                raster="elevation",
                column_prefix="rst",
                method="average",
                percentile=90)
...

2. and PyGRASS:

from grass.pygrass.modules import Module
...
    Module("v.rast.stats",
           flags='c',
           map="zipcodes_wake",
           layer="1",
           type=['point', 'line', 'boundary', 'centroid', 'area'],
           raster="elevation",
           column_prefix="rst",
           method="average",
           percentile=90)
...

[pesekon2]

It looks very nice, thanks. I found only one little stain on this otherwise magnificent piece of art. When you have an output that is not intermediate and it thus generates v.out.ogr/r.out.gdal command in the PyWPS export, the indentation in the Module command does not look so nice.

        Module("v.out.ogr",
                    input="region",
                    output=os.path.join(
                        tempfile.gettempdir(),
                        "region" + ".gml"),
                    format="GML")

[landam]

It looks very nice, thanks. I found only one little stain on this otherwise magnificent piece of art. When you have an output that is not intermediate and it thus generates v.out.ogr/r.out.gdal command in the PyWPS export, the indentation in the Module command does not look so nice.

        Module("v.out.ogr",
                    input="region",
                    output=os.path.join(
                        tempfile.gettempdir(),
                        "region" + ".gml"),
                    format="GML")

Fix in 25f007f. Now:

        Module("v.out.ogr",
               input="jena_boundary_5km",
               output=os.path.join(
                       tempfile.gettempdir(),
                       "jena_boundary_5km" + ".gml"),
               format="GML")