Make shell scripts that forwards all calls and checks for requirements etc.

[holgerm]

Reasons are:

• No cryptical "python3 w2mt.py" at the start, just something line "w2mt" instead.
• Same for "python3 w2mt_start.py", this one could even do more:
  • list all available worlds that have been created by w2mt
• Could perform a check if all requirements are given and eventually guide the user throught the process of setting up things like
  • installing the right python version
  • setting environment variables
  • ensure command line minetest is installed and useable

Questions:

• how can we do that cross platform (Windows, Linux, MacOs)?