Trade Route Smaller Minimal Duration

Reduce the minimal duration requirement for the trade route to complete, it would make the trader more flexible. Now the trade route takes at least 14 turns to complete regardless the era when the trade route start For example, the trade route of length 7 would complete with 14 turns, length 8 with 16 turns, length 6 with 24 turns. It was set as beyond 20 turns in Original game, and the number is increased in later eras (starting from Medieval Era). For example, the trade route of length 8 would complete with 32 turns. The trade route of length 5 would complete with 30 turns (if it begins in Medieval Era, then it needs 40 turns to complete). Thanks the Better Trade Screen MOD for figuring out the formula for the trade route duration, If you are using that popular MOD, please have Better Trade Screen Fix also installed to correctly show the trade route duration. The simplified Formula for trade route duration 1. N: Take the minimal duration specified by the game, and obtain the addition based on the current game era. 2. M: Obtain the actual length of the trade route. 3. ceil((N + 1) / M / 2) 2 M is the duration of the trade route, which means the number of rounds the trader need to complete. After changed to 12, the duration for trade route of length 4, 5, 6, 7, 8 is 16, 20, 24, 14, 16. The following ones would be 2m for length m.