Add helper functions for integer division rounding

Added set of functions that perform integer division with different
rounding modes:
- divideAndCeil - rounds up to next integer
- divideAndRound - rounds to nearest integer
- divideAndFloor - rounds to previous integer (equivalent to default
division)

Intended for use in library, where usage of floating point might lead to
desync in multiplayer games.

Replaced some cases that I knew of, including recent handicap PR

lib/mapObjects/MiscObjects.cpp

@@ -200,7 +200,7 @@ ui32 CGMine::getProducedQuantity() const
 {
 	auto * playerSettings = cb->getPlayerSettings(getOwner());
 	// always round up income - we don't want mines to always produce zero if handicap in use
-	return (producedQuantity * playerSettings->handicap.percentIncome + 99) / 100;
+	return vstd::divideAndCeil(producedQuantity * playerSettings->handicap.percentIncome, 100);
 }
 
 void CGMine::battleFinished(const CGHeroInstance *hero, const BattleResult &result) const