Revising code for DIVAInt paper

1. Added the new option 'rs': allow the use of rank-sum and signed rank
tests, in lieu of the default one- or two-sample t-tests.

2. The new 'rs' option can be used in conjuction with the 'permute'
option. The intermediate permutation results will be saved to mat files
named as "perm_file/*_rs.mat"

3. Tweaks for making figures, including the option for showing only the
corrected p-values: 'noUnc'

Usage example:
intShift_analysis_1(1, [1, 2], 'cpa', 'loadCache', 'rs', 'permute', 10000,
'noUnc')