making API of Literal types more intuitive.

[irina-dragoste]

Constructors of Literal types, as well of methods in Expressions utility class that construct literals use parameter name terms (of type some collection/array of Term objects) to refer to the literal arguments. This makes it tempting for the user to call getTerms() (which returns the set of terms used as arguments) instead of getArgumets() (the actual list of argument terms the literal was constructed with).

It would be useful to rename terms parameter to arguments in all these constructor methods.