generate truth table

Accepts an array of strings and returns an array representing a truth table.
Symbols: '~': negation, '&': conjunction, '|': disjunction, '->': conditional, '==': biconditional

All other values are read as a basic proposition. For example 'a==b' is read as basic propositions 'a' and 'b', joined by '=='. But 'a=b' is read as a single basic proposition. Order of operations is assumed left-to-right unless parentheses are used.

The function outputs a 2 dimensional array. Elements of the main array represent rows, and indices of the subarray correspond to columns. The top row has the string values of the propositions to be evaluated; all other rows contain truth values.