[Freeciv-Dev] purposal: split city report out of repodlgs.c

[Trent Piepho <xyzzy@xxxxxxxxxxxxxxxx>]

The client's repodlgs.c file has code for all the "reports" in the game, city
report, active units, science, and trade.  It's a very big file, larger than
the 10 smallest client .c files put together.  Most of it is the city
report.  So, how about making a new file called cityrep.c which has just
the city report code in it?

This splits the file evenly, with about 940 lines to city report stuff and
1000 to the other reports.