Introduce newFromNumericId as intermediate step to replace legacy ids

This was suggested by Daniel. Currently we do have many places in the
code where a numeric id is converted to an EntityId object in some
way. This method is supposed to be an intermediate step to get rid
of all numeric ids. If it's used (I have to do this in other patches
since it's used in other modules) it will make it a lot easier to
find and fix code that still relies on numeric ids.
Update EntityId.php
Update EntityId.php
Migrate to JSON i18n

Procedure per https://www.mediawiki.org/wiki/Manual:GenerateJsonI18n.php
with shim.
Merge pull request #33 from siebrand/json-i18n

Migrate to JSON i18n
Add new Term classes

Most of this has already been reviewed before it was merged into
https://github.com/wmde/WikibaseInternalSerialization/tree/master/DataModel

This commit moves the code to DataModel, adds tests, adds some validity
checks and adds some new getters

This is part of the evil plan to split up Entity as per
https://github.com/wmde/WikibaseDataModel/issues/22.

The new classes are essentially already used by WikibaseInternalSerialization.
Merge pull request #34 from wmde/terms

Add new Term classes
Optimize imports for tests
Replace custom classmap loading for tests with PSR-4 loader
Update AliasGroupList.php
Added Entity::getFingerprint
Added Entity::setFingerprint
Merge pull request #35 from wmde/testLoader

Replace custom classmap loading for tests with PSR-4 loader
Merge pull request #37 from wmde/getFingerprint

Added Entity::getFingerprint
Update method name as per Thiemo_WMDE
Deprecate old term related methods in Entity
Merge pull request #38 from wmde/deprecateeee

Deprecate old term related methods in Entity
Inline documentation cleanup of Entity
Merge pull request #39 from wmde/entity-doc-cleanup

Inline documentation cleanup of Entity
Add reference to reference