Added PACKET_RESEARCH_INFO. The fields of this new packet type were formely
in PACKET_PLAYER_INFO. But since the research can be team pooled, it appeared
better to have them in a separate packet.

See gna patch #4769

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@25202 a0f10bec-cc02-0410-94fc-a9cfff90b4cd