Add experimental RA procedural map generator

Add an experimental procedural map generator for the Red Alert mod,
along with supporting code that may assist in the development of map
generators for other mods.

Map generation may be accessed as a tool in the Map Editor. This change
does not presently introduce direct lobby options for generated maps.

Features:

- Terrain with land, water, beaches, cliffs, roads, debris, and trees.
- Placement of mpspawns, neutral buildings, and resources.
- Rotational and mirror symmetry options.
- Various configurable parameters with presets.
- Deterministic with configurable seed.
- Performant.

OpenRA.Game/Exts.cs

@@ -510,6 +510,11 @@ namespace OpenRA
 			return byte.Parse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
 		}
 
+		public static ushort ParseUshortInvariant(string s)
+		{
+			return ushort.Parse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
+		}
+
 		public static short ParseInt16Invariant(string s)
 		{
 			return short.Parse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
@@ -520,6 +525,22 @@ namespace OpenRA
 			return int.Parse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
 		}
 
+		public static float ParseFloatOrPercentInvariant(string s)
+		{
+			var f = float.Parse(s.Replace("%", ""), NumberStyles.Float, NumberFormatInfo.InvariantInfo);
+			return f * (s.Contains('%') ? 0.01f : 1f);
+		}
+
+		public static bool TryParseByteInvariant(string s, out byte i)
+		{
+			return byte.TryParse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo, out i);
+		}
+
+		public static bool TryParseUshortInvariant(string s, out ushort i)
+		{
+			return ushort.TryParse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo, out i);
+		}
+
 		public static bool TryParseInt32Invariant(string s, out int i)
 		{
 			return int.TryParse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo, out i);
@@ -530,6 +551,17 @@ namespace OpenRA
 			return long.TryParse(s, NumberStyles.Integer, NumberFormatInfo.InvariantInfo, out i);
 		}
 
+		public static bool TryParseFloatOrPercentInvariant(string s, out float f)
+		{
+			if (float.TryParse(s.Replace("%", ""), NumberStyles.Float, NumberFormatInfo.InvariantInfo, out f))
+			{
+				f *= s.Contains('%') ? 0.01f : 1f;
+				return true;
+			}
+
+			return false;
+		}
+
 		public static string ToStringInvariant(this byte i)
 		{
 			return i.ToString(NumberFormatInfo.InvariantInfo);
@@ -545,6 +577,11 @@ namespace OpenRA
 			return i.ToString(NumberFormatInfo.InvariantInfo);
 		}
 
+		public static string ToStringInvariant(this float f)
+		{
+			return f.ToString(NumberFormatInfo.InvariantInfo);
+		}
+
 		public static string ToStringInvariant(this int i, string format)
 		{
 			return i.ToString(format, NumberFormatInfo.InvariantInfo);