[Improvement] Signature table refactoring (many issues)

[exodus4d]

The recent changed and new features added to the "signature module" made the client side code even more complex, more vulnerable for bugs and harder to maintain. Therefore I had to made a full refactoring/rewrite of the "signature module".

What should be achieved:

• client side updates in the sig table are faster and less buggy
• added support for simultaneous editing of the same signature by multiple users
• reduced the amount of "self written code" and use more 3rd party code that is shipped with the JS libraries which are used
• many more bug fixes

The main problem that should be solved:

There are two main JS libs in use for the sig table. For table render DataTables and xEditable for the inPlace editing stuff. DataTables uses an underlaying data object cache that holds all the cell data, and xEditable just handles the editing and save/update stuff for a cell.
The problem we had is, that updates made by xEditable were not made to the DataTables table cache as well and checking the table for updates required a full DOM scan looking for xEditables fields and their current value. -> bad performance.
No we need a two-way-binding where changes made to a cell, xEditable updates the DataTables cache. And changes made to the DataTables cache (e.g. auto table update) updates the xEditable value. This will made a lot things easier...