Use MetaString in place of boost::format to avoid exceptions

lib/mapObjects/CArmedInstance.cpp

@@ -16,6 +16,7 @@
 #include "../CGeneralTextHandler.h"
 #include "../gameState/CGameState.h"
 #include "../CPlayerState.h"
+#include "../MetaString.h"
 
 VCMI_LIB_NAMESPACE_BEGIN
 
@@ -110,7 +111,12 @@ void CArmedInstance::updateMoraleBonusFromArmy()
 	else if (!factions.empty()) // no bonus from empty garrison
 	{
 		b->val = 2 - static_cast<si32>(factionsInArmy);
-		description = boost::str(boost::format(VLC->generaltexth->arraytxt[114]) % factionsInArmy % b->val); //Troops of %d alignments %d
+		MetaString formatter;
+		formatter.appendTextID("core.arraytxt.114"); //Troops of %d alignments %d
+		formatter.replaceNumber(factionsInArmy);
+		formatter.replaceNumber(b->val);
+
+		description = formatter.toString();
 		description = description.substr(0, description.size()-3);//trim value
 	}