Added Reference & Block

Added a reference in CAT and a block in CEG of Beyond the future
CSD Visual fix

The mod uses a Specialist called a 'Civil servant' that CAT lacked a
defined icon for. This fix just reuses the Great Merchant icon.
Spelling error
Artistic Genius fix

Artistic Genius should now grant +25% bonus to Great (Cultural) People
CanConstruct fix

Set Cost = -1 instead of 0 so player:CanConstruct runs correctly. Also
added extra check so all non-positive Costs are automatically set to -1.