Port of some underscore-js functions for meteor ui.
returns true if arg1 doesn't equals arg2
returns true if arg1 equals arg2
returns true if arg1 is greater than arg2
returns true if arg1 is greater or equals arg2
returns true if arg1 is lower than arg2
returns true if arg1 is lower or equals arg2
returns first value of args if arg is true returns second value of args if arg is false returns n-th value of args if arg is a number returns an empty string if nothing matches