Remove old autogenerated notice, add notice that tools/image is no longer useful.

Icons are now always in separate image files (and joined at run-time), so there is currently no tool which
autogenerates the header. The header should be updated manually, if adding new icons.

Fixes ticket:3886.
Don't let other objects set text color of desync/quit/drop icons' player numbers.

(Same for font size. — Cyp)
Merge branch 'bugfixes' into 3.1