Can we make it easier for users to define contrasts?

[julieechow]

Contrast coefficients need to be specified by the user. Would be good to be able to select the comparisons you want to make (with meaningful labels) and the program will input the corresponding coefficients for analysis - i.e. is there a way to simplify the process of contrast definitions for a user, given an lm or ez object and given an input of levels of comparison, for example?

[garner-code]

We have a function in PSY2R that may do the job. Need to check it