Simplify and extend the handling of bitmap objects in s.logo

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/ade4@667 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Correct a bug: add choices for kernel in s1d.density

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/ade4@668 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Remove some comments

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/ade4@669 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Add new functions: s1d.curve, s1d.dotplot, s1d.hist, s1d.interval

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/ade4@670 edb9625f-4e0d-4859-8d74-9fd3b1da38cb