Added script to launch GDevelop IDE
Fix functions not working with multiple scenes or with external events.

For the first issue, functions do not expose anymore a global variable.
For the second issue, functions are mangled with scene name and the search
for a function is now following links.
Fix folder opening in a file explorer on Linux and Mac
Try to find Node.js using also 'nodejs' as executable name on Linux
Prefer using 'nodejs' instead of 'node' executable on Linux