List of acquisition functions

[Balaji Pokuri]

Current implementation tends to use a list of kappa generating functions. This can often be restrictive if the user wants to use multiple kinds of acquisition functions -- not just LCB but other things like EI/PI and other custom functions.

The change should be not be tough, each acquisition function should take in 4 parameters : mean, variance, curr_best and iter. find_next_query_points() will iterate through the list of functions and not kappa.

On the flipside, this will push things onto the user to know about acquisition functions and defaults will be tough to deal with

[Balaji Pokuri]

Changes have been made in commit d1fce97. The user can now supply either a string / function/ list of strings and functions to the initialization and it should take care of properly assigning the acquisition function

[Balaji Pokuri]

commit d1fce97