Rearranged whitespace (and comments) in all the code!

The primary goal was to only indent with tabs and not mix them with spaces.
Also, no more tabs should appear past the first printable char on each line.
Now editing the sources will be much easier, no matter which editor one uses,
and rearranging won't break aligned code.
(Beware, the changeset is huge, but the `diff -w' changes are moderate.)