Change client id naming scheme

[ebruchez]

Currently:

• ids have a prefixed defined by the "container" they are within
• this means that form author controls can have ids which have prefixes

What we would like to have:

• ids in top-level scope do not have prefix
• ids have a prefixed that identifies their scope

This would also facilitate testing with tools like Selenium.

[evdwaard]

Our preference would also be to not have any $ in the id's (to help jquery work) and to not have any numbers that change when you add a field in the middle of the form. This would help keeping selenium tests working, even if the form changes.

[ebruchez]

Ernout, in 4.3, we have removed the dollar and chosen another special unicode character (≡) which doesn't bother jQuery. And yes, if we do things well, the ids of the controls produced by Form Builder should be stable.

[avernet]

+1 from customer

[avernet]

+1 from community

[ebruchez]

+1 from community

[ebruchez]

+1 from customer, for testing