propp: 'concl' patterns;
assumptions: tactics for non-goal export;
use Display.pretty_thm_no_hyps;
assm vs. assume vs. presume;
tuned type goal;
tuned print_goal;
relative exports, absolute export_thm rule;
transfer_facts;
tuned;
\@ifundefined{pdfoutput}{\usepackage{../url}}
{\usepackage[pdftex,a4paper,colorlinks=true]{hyperref}
\gdef\bold#1{\textbf{\hyperpage{#1}}}}