[BUGFIX] datepicker dateformat setting is confusing

Add manual entry to set own date-formats

related: #59319
Parent: 44b8de88 (Merge tag '2.1.2' into develop)	1
			Author: Alexander Stehlik <alexander.stehlik@gmail.com>	2
			AuthorDate: 2014-09-19 12:32:22 +0200	3
			Commit: Alexander Stehlik <alexander.stehlik@gmail.com>	4
			CommitDate: 2014-09-19 14:26:17 +0200	5
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			[BUGFIX] Prevent invalid VariablesViewHelper rendering	7
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			This patch resolves two problems when rendering powermail_rte contents.	9
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			The parseFunc wraps {powermail_all} in a paragraph tag. To prevent	11
			invalid HTML the paragraph is removed using preg_replace.	12
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			Additinally the html_entity_decode() call will return UTF-8 encoded	14
			data. This prevents problems in some PHP installations where the	15
			$nbsp; character is encoded to an invalid character.	16
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			Relates: #61118	18
			Releases: 2.1	19
			Change-Id: I1cba0b302b87f55b00033cc20f00ecfadb431ec3
[TASK] Cleanup some ViewHelpers

related: #61956
[TASK]  Form submit fails if two fields have the same marker name

Included a message that will be shown if a form has non-unique marker fields

related: #61681
[TASK]  Uploads of files with uppercase in extensionname

related: #61987
[BUGFIX] mandatory date field

Added data-attribute for parsley in date field. Date converting in model should only work if there is a value.

related: #61803
Removed unused method in ValidationDataAttributeViewHelper.php
Added some unit tests to ValidationViewHelpers,
Captcha ViewHelper for AdditionalAttributes in an own class
Some cleaning in ValidationViewHelpers
[BUGFIX] mandatory date field

Added another parsley event "change"

related: #61803
Changelog update in manual
Fixes misconverting of p-tags
correct unit test of datepicker validation attributes
Added mandatory date field to behavior tests
Added unit test to improve quality of the paragraph-remove function
Added unit test for BasicFileFunctions.php
Merge branch 'release/2.1.3'