Add support for more operations

exp, log, sqrt, pow, trig
sum(axis), max(axis), mean(axis) -> but also does that mean we have RELU? max(0, x) ?
current sum(), just one by one adds. could be much better...
==, <, >, etc -> returns an Array same shape filled with 0 and 1 for false / true respectively
ternary operator or .where(cond, x, y) setups to support if
softmax, convolutions, etc activation functions, tanh, relu