apply --whitespace fixes and enhancements.

apply --whitespace fixes and enhancements.

In addition to fixing obvious command line parsing bugs in the
previous round, this changes the following:

 * Adds "--whitespace=strip".  This applies after stripping the
   new trailing whitespaces introduced to the patch.

 * The output error message format is changed to say
   "patch-filename:linenumber:contents of the line".  This makes
   it similar to typical compiler error message format, and
   helps C-x ` (next-error) in Emacs compilation buffer.

 * --whitespace=error and --whitespace=warn do not stop at the
   first error.  We might want to limit the output to say first
   20 such lines to prevent cluttering, but on the other hand if
   you are willing to hand-fix after inspecting them, getting
   everything with a single run might be easier to work with.
   After all, somebody has to do the clean-up work somewhere.

Signed-off-by: Junio C Hamano <junkio@cox.net>