Realistic Horse Genetics

Backported these changes from the 1.15 series: Gene book renamed to breeder's guidebook, plus some minor adjustments Slightly adjusted graying and simplified its configuration Added pregnancy progress indicator. This is a bar next to the gender icon that fills up as the pregnancy progresses. Horses no longer stop to rear when damaged by suffocation or cactus, instead they will hopefully do something more sensible like move away Tobiano is now listed separately from KIT in the genetic test results Some adjustments to shade. Lighter buckskins and palominos and darker horses of all colors are possible now. Some horses may lose their summer dapples / condition dapples.