DRAGANDDROP.md, PROTOCOL.md: Doc for "drag'n' drop" implementation.
dragAndDrop.php: API endpoint
DragAndDrop.php: Class for implementing drag'n' drop functionality.
Link.php: implement new renderMode=8 - returning only the sip.
QuickFormQuery.php: New entry point for processing "drag'n' drop".

delete.php: it seems that assign an array element to a string variable does not convert the string to an array. CR thought this was the case in the past (maybe a change in PHP7.2)

Unknown index fixed by isset()

Buf #4257 / Dynamic update broken - after changing JSON data structure, update load.php has been missed.

save.php, QuickFormQuery.php: fixed malformed array for JSON
Dirty.js, QfqForm.js: replace instance variable 'additionalQueryparameters' against parameter by call: optionalQueryParameters.

delete.php: process json answer of qfq-delete()
Dirty.php: More specific error message. In case of locking problem during form delete - return json and not an exception.
QuickFormDirty.php: Code cleanup. Interpret answer of dirty->checkDirtyAndRelease

file.php, load.php, Html2Pdf.php: minor updates.
Dirty.php, QuickFormQuery.php: optional $lockTimeout as parameter during instantiating. Return $lockTimeout where necessary. Otherwise read qfq.config.ini. Refactor process(), acquireDirty(), checkDirtyAndRelease().

typeahead.php: An exception catched in typeahead.php has been assigned as array element, instead of a whole array. Fixed.

First implementation on server side: only tag as dirty, no check during save().
dirty.php, Dirty.php, Client.php: new
Store.php: refactored fillStoreClient() to use an dedicated class.
BuildFormBootstrap.php: add hook for dirty.php

QfqForm.js: Preparation for client, to handle window.location.replace() by new API status 'url-skip-history'. Also changed "(data.redirect === "url" || data['redirect-url'])" to "(data.redirect === "url" && data['redirect-url'])" - CR did not understand the former logic ('or' instead of 'and'). #OPEN#: window.location.replace = 'index.php....' throws an JS exception that it the attribute 'replace' is readonly. Instead "window.location.replace('index.php....')" works as expected.
PROTOCOL.md: add 'url-skip-history'.
save.php: recode to become more readable.
QuickFormQuery.php: getForwardMode() - temporarily fix to update status 'page' to 'url' (bug never caused a problem as long as '||' has been used on client side). Will change 'page' to 'url' asap.

* Recode the '_link' notation for download
* Add 'ZIP' as export format
* Add 'parameter' to wkhtmltopdf
* Implemented 'SYSTEM_STORE / SYSTEM_DOWNLOAD_POPUP' for detecting if there are download links on the page. This eleminates passing parameters through dozens of functions.
* Report/Columntype '_dDownload' broken!
Coding.md: described `download` from a coding point of view.
Manual.rst: Update '_link' to latest notation of 'download'.
download.php: implemented catching of 'Undefined index'. Added further exceptions.
Download.php: Added cache=off for downloading. Rename getFile() to getElement(). Make getElement() more generic. Add zipFiles(). Implement 'downloadMode' in doElements().
Html2Pdf.php: recode to new download notation. Parameter to wkhtmltopdf implemented.
Link.php: New TOKEN_* and NAME_DOWNLOAD_*, NAME_FILE. Move TOKEN_* to Constants.php. Will be used in Download.php too. Implemented 'SYSTEM_STORE / SYSTEM_DOWNLOAD_POPUP'. Implemented BASE64 encoding of multiple 'U' and 'u'.
Report.php: Implemented 'SYSTEM_STORE / SYSTEM_DOWNLOAD_POPUP'.
Sip.php: implement debugSip() to show Sip. New: base64 encoded parameter will be shown in clear.
Store.php: some functions missed keyword 'static'. getVar() and getStore automatically decode base64 parameter.
QuickFormQuery.php: Implemented 'SYSTEM_STORE / SYSTEM_DOWNLOAD_POPUP'.

Implemented download.php to offer SIP protected downloads for single files (any filetype) as well as concatenated PDF files and converted HTML pages.
download.php: API Interface
DownloadException.php: New exception class for downloads - might be extended for better error handling.
OnArray.php: new function getArrayItemKeyNameStartWith() to filter for specific elements in an array. New function arrayEscapeshellarg() to escape args
Download.php: Main class.
Link.php, Report.php: implemented new link type 'd' (=download)

Split PHP 'print.php' in a pure API file 'print.php' and a class 'Html2Pdf.php' - the class will be reused by Download.php

The new class T3info() was fine, but relying classes assumed that all array elements always exist. This was not given in the past. The new implemention creates at least an empty entry for each element.
AbstractException.php: removed garbage line.
save.php: require_once missing PHP Exception classes.
T3Info.php: recode.

#3431 / typeAheadSql: columnname 'key' is a reserverd SQL statement - replace by 'id'. Additional the parametername 'typeAheadLdapKeyPrintf' renamed to 'typeAheadLdapIdPrintf'.
typeAhead.php: fixed typo.
TypeAhead.php: introduced new mapping from 'id' (SQL) to 'key' (API).
AbstractBuildForm.php: Constant renamed.
Database.php: update function makeArrayDict() to reflect name mapping.