clarified Document.Snapshot.all_exports: refer to material from this (virtual) session;
clarified treatment of Session_Context.theory_names, added export_names;
clarified treatment of document_snapshot: sites on top of the session_stack;
lukas.bulwahn@gmail.com = bulwahn
chaieb@chaieb-laptop = chaieb
eberlm@in.tum.de = eberlm
Manuel Eberl = eberlm
bertram.felgenhauer = felgenhauer
bertram.felgenhauer@uibk.ac.at = felgenhauer
Mathias.Fleury@mpi-inf.mpg.de = fleury
Gerwin Klein <gerwin.klein@nicta.com.au> = kleing
hellerar@macbroy24.informatik.tu-muenchen.de = hellerar
brianh@cs.pdx.edu = huffman
lars.hupel@mytum.de = hupel
immler@in.tum.de = immler
markus.kaiser@in.tum.de = kaiser
cezarykaliszyk@gmail.com = kaliszyk
kaliszyk@in.tum.de = kaliszyk
gerwin.klein@nicta.com.au = kleing
rafal.kolanski@nicta.com.au = kolanski
lammich@in.tum.de = lammich
Andreas Lochbihler = lochbihler
daniel.matichuk@nicta.com.au = matichuk
Philipp Meyer = meyerp
nipkow@lapbroy100.local = nipkow
noschinl@in.tum.de = noschinl
Lars Noschinski <noschinl@in.tum.de> = noschinl
Stephen W. Nuchia = nuchia
lcp = paulson
lp15@cam.ac.uk = paulson
Jean Pichon = pichon
norbert.schirmer@web.de = schirmer
schirmer@in.tum.de = schirmer
griff = sternagel
Christian Sternagel = sternagel
nik = sultana
Timothy Bourke = tbourke
rene.thiemann@uibk.ac.at = thiemann
thomas.sewell@nicta.com.au = tsewell
tsewell@nicta.com.au = tsewell
tsewell@rubicon.NSW.bigpond.net.au = tsewell
urbanc@in.tum.de = urbanc
wimmers@in.tum.de = wimmers