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
Add reference to reference
Make Term non-abstract and add field type checks
Add setLabel to fingerprint
Merge pull request #40 from wmde/refref

Add reference to reference
Merge pull request #41 from wmde/terminst

Make Term non-abstract and add field type checks
Make TermList mutable and add use a more straightroreward approach to adding labels
Merge pull request #42 from wmde/setlabel

Add setLabel to fingerprint
Add hasTermForLanguage and removeByLanguage to TermList
Add setDescription to DescriptionList
Merge pull request #43 from wmde/termlist

Add hasTermForLanguage and removeByLanguage to TermList
Added setGroup and removeByLanguage to AliasGroupList
Merge pull request #45 from wmde/aliaslist

Added setGroup and removeByLanguage to AliasGroupList
Merge pull request #44 from wmde/DescriptionList

Add setDescription to DescriptionList
TermList::removeByLanguage no does no-op when no term is found
Merge pull request #46 from wmde/noop

TermList::removeByLanguage no does no-op when no term is found
Filter empty groups out in AliasGroupList constructor
Filter empty groups out in AliasGroupList::setGroup