Merge branch 'hotfix/#5962-mime-empty-string-on-no-part'

Close #5962
Close #6157
Hotfix for UnderscoreNamingStrategy for 2.3, will be fixed properly in 2.4
#6207 - removing unused `@group` annotation
Merge branch 'hotfix/#6207-underscore-naming-strategy-not-studlycase'

Close #6207
Merge branch 'hotfix/#6207-underscore-naming-strategy-not-studlycase' into develop

Close #6207
Forward Port #6207
Fixes typo algorihtm -> algorithm
Merge branch 'typo/#6213-typo-fix'

Close #6213
Merge branch 'typo/#6213-typo-fix' into develop

Close #6213
Forward Port #6213
* added MutableCreationOptionsAwareTrait
Update MutableCreationOptionsAwareTrait.php
Create MutableCreationOptionsAwareTraitTest.php

* added unit test for MutableCreationOptionsAwareTrait
Update MutableCreationOptionsAwareTraitTest.php

added requires annotation
Update MutableCreationOptionsAwareTraitTest.php

removed trailing space in docblock
Update MutableCreationOptionsAwareTrait.php

changed copyright information to 2014
* fixed array notation
* improved options array readability
* fixed @requires annotation
* explicitly skipping unit tests on PHP Version < 5.4  as "@require" wouldn't suffice
* removed "Aware" from Classname
* Removed leading \  from Zend namespace in unit test
* Removed @group annotation from unit test
Merge branch 'feature/mutable-creation-options-traits' into develop

Close #6175