Add try-catch to addScript in DependencyManager

[ultimate]

This way it is possible to determine whether the script was really loaded or not...

[ultimate]

Unfortunately this does not seem to be trivial:
Within addScript the behaviour is as followed (explanation below):

1. check whether a script node exists for the given id
2. of not add a new empty script node
3. otherwise eval() the script
4. set the text content of the script node to the script

When setting the text content of a script node for the first time, the content is evaluated by the browser automatically. When updating the content this does not happen! So it is necessary to evaluate the new content manually. But while eval() will throw an exception that may be caught using try-catch, the browser won't on setting the text content since this is not a function call and the evaluation is seems to be done somewhere else (asynchrounously?).

[ultimate]

So there are the following options which come to my mind:

1. no use of the script tag at all - all scripts will be evaluated manually and only be stored in the EntityManager - no script will appear in the DOM
2. no try-catch - everything stays as it is - no detection of erronous scripts
3. evaluate before script tag - scripts will be executed twice - this may cause side effects...
4. adding script tags with dummy content - so this content will be evaluated - afterwards the script tag's content may be replaced and the script must be evaluated manually