rename file.
use det_AtA to calc det of X'X.
add test of det_AtA
Add some documents and fix some typoes
fix minor errors of Rcheck, add tests of lm.resid
use match.arg
update doc
new method of running test, from https://github.com/hadley/testthat
update parameter names in testpleio.1vs2.
add print function.
create test of testpleio.1vs2 and testpleio.1vsp
mv tests files to tests/testthat
update parameter names in vignette
fix format problem.