Dissolution of marriage — Attorney’s fees — Where marital settlement agreement included a “defaulting party” provision for fee-shifting in post-judgment proceedings, trial court did not abuse discretion in awarding former husband attorney’s fees and costs incurred in connection with former wife’s numerous unsuccessful post-judgment claims and motions — Fact that some of former wife’s claims were termed “frivolous” or “vexatious” in final order does not transform it into an order awarding statutory or common law sanctions