Add notes about 'might be clobbered' on longjmp()

Add and modify notes about nearly incident points
Add links to Tomilov's qhullhull.hpp
Add note about scipy's use of Qhull
Suggestion: Add Octave's created endpoints for unbounded ridges [M. Voss]
FAQ and suggestions: post-merge pass for slivers [M. Treacy]
Add notes from Pavia and Zhang
Fix links