Cleanup Melusine Configurations

[Hugo Perrier]

Description of Problem:
The way configs are handled in Melusine is not ideal:

• A ConfigJsonReader class object is instanciated at the beggining of each module
• The conf files are read multiple times
• Using custom configurations is more complex than it should be
• The csv format for the names file is not robust

Overview of the Solution:
The following changes are suggested:

• Load the configs once and import them in modules with a simple import statement
• Use an env variable to specify a folder containing custom configuration files
• Change the format of the names file

Examples:

os.environ["MELUSINE_CONFIG_DIR"] = "path/to/custom/config/dir"
from melusine import config
print(config["words_list"])