Single entry point to run all tools

[tbouffard]

We are going to have several tools, so introduce a single entry point (java class) and options for usage simplicity:

• do not force user to choose a dedicated main class for each tool
• keep startup as simple as possible, java jar + options
• by default, we could start the svg2xml GUI (as today)

Possible usage: <java_cmd> <tool_name> [options] Example: java -jar xxx.jar svg2js <path_to_svg_input_file>