Bug fixes:
o Baselining samples correctly returns error when there are no
    appropriate samples to baseline with.
o Custom y-lim now redraws axes to include zero, in those cases where
    ymin = ymax
o Selecting a single sample correctly works. Before the matrix was
    erroneously being converted to a numeric vector.
o Default zero reference line removed to improve visibility of zero line
o version updated to beta 1.2.