Normalisr

Updated reference.

Bug correction for parameter single in normalisr.de.de not being passed through correctly.
Updated documentation.
Compatibility updates.

Added new association test normalisr.association.association_test_5 that uses given mask to determine X-Y pairs in hypothesis tests with multi-variate regression. This option is not yet available on command line.
Refactored normalisr.association, normalisr.de, and normalisr.coex.
Added option 'lowmem' to reduce memory footprint by not returning regression coefficients of covariates.

Parallelled lcpm
More error messages and documentation
Adding memory efficient options in several functions as the default
Updated examples accordingly

Updated dependency and examples.

Updated documentation.