Fixed Bug #7335

Modified several gvg checks to include checking whether it is a guild castle ( map_flag_gvg2 does so and no it doesn't mean woe:se )
Special Thanks to kyeme.
http://hercules.ws/board/tracker/issue-7335-woe-castle-behavior/
Also follow up 24ced6fcef1a95a2abd0c60b4fe90cbbc3aea268 changed 512 with its constant, special thanks to EPuncker.

Signed-off-by: shennetsind <ind@henn.et>