[2904737] - fix BOM back compatibility
[2910358] - Error in context when Key field is found in different tabs.
[2910368] - Error in context when IsActive field is found in different
[2871039] - Tax Rate Parent window not working
Guarantee backward compatibility with previous approach
Added method to get tab context variables without defaulting to window or login variable (required safety measure)
Some refactorings to improve reading and performance
Reactivate hidden tabs - and move back BOM & Formula window to manufacturing menu
Carlos Ruiz