[CLI] Added new options

[simogasp]

This PR introduces two main options to the command line scripts.

• meshroom_photogrammetry, a --overrides parameter is added that enables the user to specify a json file containing parameters values to use for each node, thus overriding the default settings. The json file follows a similar structure of the .mg file containing the pipeline, ie:

{
        "<node1Name>": {
                "<param1Name>": "<param1Value>"
                "<param2Name>": "<param2Value>"
        },
        "<node2Name>": {
                 "<param1Name>": "<param1Value>"
        },
...
}

For example one file setting file settings.json could be

{
        "FeatureExtraction_1": {
                "describerPreset": "high"
        },
        "FeatureMatching_1": {
                "guidedMatching": "0"
        },
        "StructureFromMotion_1": {
                "useLocalBA": "0",
                "refineIntrinsics": "0"
        }
}

• ui can now take a parameter --pipeline --project that enables the user to specify a project file to load, i.e.

python meshroom/ui --project myProject.mg

Moreover, it add the possibility for the node PrepareDenseScene to export the list of undistorted images so they can, eg, published with the Publish node. This is because there was no other way of export the images since the suppression of the node ExportUndistortedImages (490ebfe)