beamer: introduce diagnostics

    * beamer.tex (Internals): Here.
    * bison.png, gcc.png: Include these graphics.
Merge branch 'master' of https://github.com/nitnelave/bison-pres

* 'master' of https://github.com/nitnelave/bison-pres:
  beamer: remove leftover from merge
  beamer: expanded mid-values, testsuiteflags
  beamer: ugly fix for the tilde in url
  beamer: removed prologue and epilogue from getting started
  beamer: operator precedence

Conflicts:
	beamer.tex