Change: Allow AI companies to start immediately.

Allow multiple AIs to possibly start in the same tick.
start_date = 0 becomes a special case, where random deviation does not occur.
If start_date was not already 0, then a minimum value of 1 must apply.

src/ai/ai.hpp

@@ -32,7 +32,7 @@ public:
 		START_NEXT_EASY   = DAYS_IN_YEAR * 2,
 		START_NEXT_MEDIUM = DAYS_IN_YEAR,
 		START_NEXT_HARD   = DAYS_IN_YEAR / 2,
-		START_NEXT_MIN    = 1,
+		START_NEXT_MIN    = 0,
 		START_NEXT_MAX    = 3600,
 		START_NEXT_DEVIATION = 60,
 	};

src/ai/ai_config.cpp

@@ -118,3 +118,14 @@ void AIConfig::SetSetting(const char *name, int value)
 
 	ScriptConfig::SetSetting(name, value);
 }
+
+void AIConfig::AddRandomDeviation()
+{
+	int start_date = this->GetSetting("start_date");
+
+	ScriptConfig::AddRandomDeviation();
+
+	/* start_date = 0 is a special case, where random deviation does not occur.
+	 * If start_date was not already 0, then a minimum value of 1 must apply. */
+	this->SetSetting("start_date", start_date != 0 ? max(1, this->GetSetting("start_date")) : 0);
+}

src/ai/ai_config.hpp

@@ -34,6 +34,7 @@ public:
 
 	/* virtual */ int GetSetting(const char *name) const;
 	/* virtual */ void SetSetting(const char *name, int value);
+	/* virtual */ void AddRandomDeviation();
 
 	/**
 	 * When ever the AI Scanner is reloaded, all infos become invalid. This