adding session engine section to sysadmin docs
giving more links to the Django doc
replacing prerequisites by the link to Django doc
links distinction
fixing spelling mistakes
adding Django clearing-the-session-store link
removing space
adding SESSION_EXPIRE_AT_BROWSER_CLOSE and SESSION_COOKIE_AGE
adding clearsessions to the windows doc
describe repository template path expansions
add further clarification to template path rules
add some template expansion examples
clarify behavior of %subdirs%
suggestions from @jburel
suggestions from or inspired by @pwalczysko
clarification suggested by @manics
suggestions from @pwalczysko and @ximenesuk
merge develop -D org: PR 799 (Linux walkthrough (rebased onto develop))
merge develop -D org: PR 824 (OME DCO)
merge develop -D org: PR 834 (Session engine)