Add training materials

[gardan]

In the Training Details, we should have an extra Tab with Training Materials. This will be a list of documents (pdf, doc, jpeg, etc) that the teacher wants to share with his students.

As a lot of courses will just reuse the same documents , these should be added only one time in the Settings button for each available subject and be reused from individual trainings. Deleting the document from the trianing does not delete the file , just deletes the link from the trinaing to the file.

In the settings a user with a special claim for this should be allowd to add documents. The system should record the document, the subject to which it belongs, a small description for the document, who added the document, and the date of adding it. Once a document is added in the system, it is visible to be added as a link into the trainings for the subject the document belongs to.

[imaximix]

Given that it is possible to have more than one trainer for the same subject. Should we just share all the materials? Every trainer usually has it's own materials, right?

[imaximix]

Just make it belong to a subject. It is their job to handle the materials that don't belong to them.

[imaximix]

Technical note. A size limit needs to be imposed. By default it's very small, I think 4096 KB ( 4MB ).