Adding old hacks (not included into 1.3.6) into release-1.3 branch

Adding old PRs and hacks of 1.3 branch, lost in 1.3.6 release.
=============================================
| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #801,#598,#593,#616,#617,#618,#621,#564
| Refs tickets  | 
| License       | MIT
| Doc PR        | -

Some details:

#801 (incl #665) -> PR #924 - 'extmenu drag and drop1 -> /system/Admin/javascript/admin_admin_ajax.js
	
#598 -> 'EntityAccess::toArray - don't call non existing methods' -> lib/Zikula/EntityAccess.php
	
#593 -> PR #607 ->'Get modimage by ModUtil::getModuleImagePath()' -> lib/util/ModUtil.php, lib/viewplugins/function.modgetimage.php, system/Admin/lib/Admin/Controller/Admin.php, system/Admin/templates/admin_admin_header.tpl
	
https://github.com/zikula/core/commit/55a22f14ca40aadc046017d39bd664c142181eef -> 'replaced double quotes with single quotes in gettext string, because it gave E_NOTICE' ->system/Extensions/templates/extensions_hookui_hooks.tpl
	
PR #616,#617,#618  -> /lib/dbobject/DBObject.php I DBObjectArray.php
	
#621 -> PR #622 -> /style/core.css
	
#564 ->  /system/Admin/templates/admin_admin_developernotices.tpl