Shorten string representations

The new format for representing timeline, province, and season is T-PRO@S. Hopefully this is easier to read than the PRO T:S format.

MultiversalDiplomacy/Model/ModelExtensions.cs

@@ -0,0 +1,23 @@
+namespace MultiversalDiplomacy.Model;
+
+public static class ModelExtensions
+{
+    /// <summary>
+    /// Short representation of a <see cref="UnitType"/>.
+    /// </summary>
+    public static string ToShort(this UnitType unitType)
+        => unitType switch
+        {
+            UnitType.Army => "A",
+            UnitType.Fleet => "F",
+            _ => throw new NotSupportedException($"Unknown unit type {unitType}"),
+        };
+
+    /// <summary>
+    /// Short representation of a multiversal location.
+    /// </summary>
+    public static string ToShort(this (Province province, Season season) coord)
+    {
+        return $"{coord.season.Timeline}-{coord.province.Abbreviations[0]}@{coord.season.Turn}";
+    }
+}

MultiversalDiplomacy/Model/Unit.cs

@@ -51,7 +51,7 @@ public class Unit
 
     public override string ToString()
     {
-        return $"{this.Power} {this.Type} {this.Province} {this.Season}";
+        return $"{this.Power.Name[0]} {this.Type.ToShort()} {(this.Province, this.Season).ToShort()}";
     }
 
     /// <summary>

MultiversalDiplomacy/Orders/ConvoyOrder.cs

@@ -37,6 +37,6 @@ public class ConvoyOrder : UnitOrder
 
     public override string ToString()
     {
-        return $"{this.Unit} convoys {this.Target} -> {this.Province} {this.Season}";
+        return $"{this.Unit} C {this.Target} -> {(this.Province, this.Season).ToShort()}";
     }
 }

MultiversalDiplomacy/Orders/MoveOrder.cs

@@ -36,7 +36,7 @@ public class MoveOrder : UnitOrder
 
     public override string ToString()
     {
-        return $"{this.Unit} -> {this.Province} {this.Season}";
+        return $"{this.Unit} -> {(this.Province, this.Season).ToShort()}";
     }
 
     /// <summary>

MultiversalDiplomacy/Orders/SupportHoldOrder.cs

@@ -14,6 +14,6 @@ public class SupportHoldOrder : SupportOrder
 
     public override string ToString()
     {
-        return $"{this.Unit} supports {this.Target}";
+        return $"{this.Unit} S {this.Target}";
     }
 }

MultiversalDiplomacy/Orders/SupportMoveOrder.cs

@@ -36,7 +36,7 @@ public class SupportMoveOrder : SupportOrder
 
     public override string ToString()
     {
-        return $"{this.Unit} supports {this.Target} -> {this.Province} {this.Season}";
+        return $"{this.Unit} S {this.Target} -> {(this.Province, this.Season).ToShort()}";
     }
 
     public bool IsSupportFor(MoveOrder move)