Added tags to scene elements
Added "Add Action" Action
Simplified tags processing. Now, tags are recursively searched, instead of cached in initialization
Merge pull request #54 from anserran/tags

Wonderful. Nice piece of code. Merging.
Added tags to scene elements and an "Add Action" action
Merge branch 'master' of https://github.com/e-ucm/ead
Merge branch 'master' of https://github.com/jtorrente/ead