Cleaned out Qt4 support code from qt-client

See patch #4607


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24757 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Added ruleset effects for Handicapped AI.

See patch #4605


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24758 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Improved messages about new extra building technologies.
- If there's just one extra type automatically built to city centers, mention
  that extra type in the message
- Omit "New hope sweeps..." -message if less than 75% of city centers get updated

Requested by Jacob Nevins <jtn>

See patch #4405


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24759 a0f10bec-cc02-0410-94fc-a9cfff90b4cd