Deleting entity record

[rgonek]

• Display more info about deleting entity
• Display form for delete options
• Logic for cascade delete
• Logic for set to null

Available delete options:

• nothing
• set null
• cascade delete
• ask user

[rgonek]

Deleting now works very well, but still need some work.

• Optimization (use WHERE ProductId IN (...))
• For cascade delete we need check what to do with sub entities in deeper levels, now we do cascade delete for every sub entity