Fixed issue #7224: comparison of dates (partial fix)

Dev: LEMval() now returns answers to date questions in yyyy-mm-dd HH:MM
Dev: format, independent of the date format that is chosen for the
question
Dev: or the particular survey. Thus, comparisons between different date
Dev: questions are possible (e.g. relevance or validation equations
Dev: "arrivaldate > departuredate") even when one question is in
Dev: dd.mm.yy and the other in mm/dd/yyyy HH:MM format
Dev: (same or previous page).
Dev: qanda_helper.php: min/max logic had to be changed accordingly
Dev: and is less complicated now.
New feature #8524: implements min/max date in EM

Dev: implements min/max date in EM (so dates are validated and
Dev: the correct help messages appear). Adv. attributes min/maxdate
Dev: in date/time question supports yyyy, yyyy-mm-dd,
Dev: questioncode (another date question) and expressions
Dev: (eg. date(Y-m-d H:i, strtotime(birthdate)+60*60*24*365*18).
Fixed issue #8484: expressions in min/max date referring to questions on same page

Dev: Expressions in adv. attribute min/maxdate also work for the date
picker
Dev: if variables in the expression refer to questions on the same page.
Dev: better hiding of a hidden element (min/max date)

Dev: Thank Shnoulle!
Dev: date format in help message now matches question date format
Fixed issue #8531: Wrong date format for [code].shown (EM)

Dev: .shown used to work only if referred date question
Dev: was on the same page. Now also on following pages.
Updated translation: Czech by slansky
Updated translation: Armenian by Satenik
Updated translation: Norwegian (Bokmål) by pmonstad
Updated translation: Dutch by Han
Updated translation: Norwegian (Nynorsk) by pmonstad
Updated translation: Russian by vipgroup
Updated translation: Tagalog by avevengers, arriz08, lolskidoodles
Updated translation: Zulu by Tanita93, cmkeet
Updated translation: Dutch (Informal) by Han
Fixed issue #8544: Missing translation
Dev Partial fix
Fixed issue #8543: Missing translation during installation
Dev Partial fix
Release 2.05+ Build 140116
Fixed issue #08477: a clear error message is now displayed when a session expires
Fixed issue #08477: a clear error message is now displayed when a session expires
Dev Also reverted commit 22b0ced540286ea6c0d796ea64ef8009007c400e
Fixed issue #8526: No information when trying to install with php < 5.3
Fixed issue #8526: No information when trying to install with php < 5.3
Fixed issue #8551: Can't add a new user if AuditLog plugin is activated
Fixed issue #8512: Matrix question in dropdown presentation shows obsolete "Please choose..." in dropdown
Fixed issue #8530: "Return to label set administration" button not working properly - patch by dkep
Fixed issue #8519: Error during upgrade vom 2.00 to 2.05 using PostgreSQL
Dev: Update for strtotime.js
Fixed issue #8519: Error during upgrade vom 2.00 to 2.05 using PostgreSQL
Dev Also fixed non-appearing inputs for username and password in login mask when using Postgres