Adds following functions to the Engine singleton:
get_author_info - names of Godot authors
get_copyright_info - detailed source copyright get_license_info
get_donor_info - donor names
get_license_info - full text of licenses used, indexed by license names
get_license_text - the text of the Godot Expat license
Using `misc/scripts/fix_headers.py` on all Godot files.
Some missing header guards were added, and the header inclusion order
was fixed in the Bullet module.
- Show ItemLists in single column if not enough item, or is a
special section (Gold/Platinum sponsors)
- Add a space before and after names so that it looks a bit
better for long names adjacent to another
- License text in monospace
