Bug 2172 - AbstractGeneratedTypeBuilder check for duplicate elements.

Check for duplicity of added elements has been added into add* methods
in the AbstractGeneratedTypeBuilder class.

Change-Id: I9ef4caef0a835c0e171e86c2b322c3452bdaada0
Signed-off-by: pkajsa <pkajsa@cisco.com>
(cherry picked from commit b1e2b02d59a05fdca07cb469712d9872a1d84bb1)
Bug 2191: Invalid use of addType in ChoiceCaseBuilder

1) in CoppyUtils removed from method copy functionality about copying
   typedefs and grouping from old ChoiceCaseBuilder, which throw in
   this implementation YangParseException

2) in AbstractDocumentedDataNodeContainerBuilder removed final modifier
   from method addGrouping because this method must be overriden in
   ChoiceCaseBuilder to throw YangParseException

3) in ChoiceCaseBuilder were overriden addGrouping method to throw
   YangParseException becaouse by RFC 6020 is not allowed that
   choice case has grouping

Change-Id: Ic06524f3489a36c73f07c8b44701895dc0e9896e
Signed-off-by: Ladislav Borak <lborak@cisco.com>
(cherry picked from commit 5eb73b6c47326147af391608ee22ab8f8ab2c87c)
Merge "Bug 2172 - AbstractGeneratedTypeBuilder check for duplicate elements." into stable/helium