Subject to sections 15(5) and 83(1) above in particular, and to any other provision of this Act which otherwise expressly provides, nothing in this Act shall prejudicially affect any power, right or remedy of a landlord, tenant or other person vested in or exercisable by him by virtue of any other Act or law or under any custom of the country or otherwise, in respect of a contract of tenancy or other contract, or of any improvements, deteriorations, waste, emblements, tillages, away-going crops, fixtures, tax, rate, tithe rentcharge, rent or other thing.