Add options to compare.sh
Add usage comment to compare.sh
Simplify mkblocks.sh

 - use bash instead of sh because of `echo -e`
 - beware the output has changed! tac and tr are no longer run
   in the end
Simplify and extend xsel.sh

 - add variants for pbcopy on Mac and plain "Press ENTER to continue"
   with printing the line on stdout
Merge branch 'jasan'