[CLI] Check the required parameters

[delhomer]

The CLI defines kpconv preprocess, kpconv train, kpconv test, kpconv visualize and kpconv plotconv. These commands share parameters, some of them are required for a subset of commands. One should doublecheck the parameter list and if they should be required for each command.

[AuBousquet]

kpconv visualize, kpconv plotconv have been given up in this branch. They are not used in the context of this project. The original .py files are kept in the sources, but they are not available from the command line interface anymore.

The documentation has been updated, to present the CLI options, for each command.

With the current version of the python code, it is not possible to avoid having the two options -f and -d for the kpconv test command, since the program calls the -d datapath at two lines, here and there. Apparently, the data used to train the model are still necessary for the test step.

[AuBousquet]

#22