In all actions tried upon the facts without a jury or with an advisory jury, the court shall find the facts specially and state separately its conclusions of law thereon and direct the entry of the appropriate judgment; and in granting or refusing interlocutory injunctions the court shall similarly set forth the findings of fact and conclusions of law which constitute the grounds of its action. Requests for findings are not necessary for the purposes of review. Findings of fact shall not be set aside unless clearly erroneous. In the application of this principle regard shall be given to the special opportunity of the trial court to judge the credibility of those witnesses who appear personally before it. The findings of the master, to the extent that the court adopts them, shall be considered as the findings of the court. If an opinion or memorandum decision is filed, it will be sufficient if the findings of fact and conclusions of law appear therein. Findings of fact and conclusions of law are unnecessary in support of a judgment by default, an interlocutory order, on decisions of motions under Rules 502 or 505 or any other motion except as provided in Rule 123; in all instances findings of fact and conclusions of law may be waived by stipulation of all parties upon approval by the court. A written memorandum decision issued by the court may constitute the findings of fact and conclusions of law only if the decision expressly so states or if it is thereafter adopted as the findings of fact and conclusions of law by order of the court.