read_file.rb works; double free error on exit from read_file.rb
Fixed double-free crash; probably broke scaling in Frame::Video

Need to figure out correct behavior for calling avpicture_alloc() and
avpicture_free().  For the time being frame scaling will not work correctly
because the destination frame has no memory associated.  Also has implications
for buffered output.
fixed memory leak in Reader.each_frame(); added PTS code
scaling complete; added in scale and seek examples