remove auto h1 splitting

this seems to be covered in the case of NO !slide markers by the code
above that inserts the !slide markers.  i think that is fine, plus it
was breaking even the example preso.

lib/showoff.rb

@@ -130,12 +130,6 @@ def process_markdown(name, content, static=false, pdf=false)
         line = lines.shift
         if line =~ /^<?!SLIDE(.*)>?/
           slides << (slide = Slide.new($1))
-        elsif line =~ /^# / && !slide.empty?
-          # every H1 defines a new slide, unless there's a !SLIDE before it
-          # todo: make this a CL option
-          # todo: unit test
-          slides << (slide = Slide.new())
-          slide << line
         else
           slide << line
         end