Add the deprecated Claim handler functions to Property

Right now these deprecated functions don't fullfil their contract,
as the abstract Entity is not properly implementing them (which is
ok as these function are being phased out).

This is needed in order to actually make the Wikibase code that
still relies on these old functions work with properties (which
is something that used to work in the past when this code was still
in Entity).

Mid-term we will want to remove all usages of these functions and
then phase them out, but for now they should at least be properly
implemented (-> fullfiling their contract).

The code and the tests were copied from item, with only very minor
adjustments.
Add two more filter methods to StatementList
Avoid in_array
Remove unsupported call
Fix some Scrutinizer issues
Use isEmpty
Drop odd Entity test
Optimize imports
Merge pull request #302 from wmde/oddTest

Drop odd Entity test
Add TermFallBack.
Add AliasGroupFallback.
Merge pull request #303 from wmde/optimize

Optimize imports
Merge pull request #300 from wmde/scrutIssues

Fix some Scrutinizer issues
Merge pull request #295 from wmde/sl

Add two more filter methods to StatementList
Merge pull request #272 from wmde/languageFallBack

Add requirements for language fall backs.
Merge pull request #280 from wmde/propertyClaims

Add the deprecated Claim handler functions to Property
Update RELEASE-NOTES.md
Fix version numbers
2.4.0 rel
Merge pull request #305 from wmde/relz

2.4.0 rel