public void upgradeToSlow()
{
type = towerTypes.slow;
}
public void upgradeToPoison()
{
type = towerTypes.poison;
}
public void upgradeToBurn()
{
type = towerTypes.burn;
}
//Series of upgrade functions to upgrade tower to different type
public void upgradetoFreeze()
{
type = towerTypes.freeze;
}