[TYPO3-mvc] cleaning up my extension, removing core hacks

[Philipp]

1) match_fields setting
I found that i am not the first to report this, some say extbase should not handle this kind of relation so i think you are still in discussion about that topic. For my extension its absolutely neccessary, i use sys_category for tagging and extbase makes some mistakes in reading the category relations of the model.

2) self-joins
Extbase cant do self-joins, so when i want to get all models with a parent having a specific attribute
matching->contains('parent.tags',tag)
extbase will throw an exception. Here i altered the addUnionStatement method, so it generates aliases for tables in joins. So, if a table is allready set i use the propertyname as alias (if that also exists for some reason i render a unique tablename).

3) In the AbstractFormFieldViewHelper i added the possibility of handling arrays with subProperties... Needed that for my demand-handling.