Improvements #9207

Updated by Roel Standaert about 1 year ago

`WBootstrap4Theme` and `WBootstrap5Theme` will not be released in an entirely complete state, in the interest of getting Wt 4.6.0 out of the door as soon as possible. 

 This issue tracks any follow up issues in `WBootstrap5Theme` that we still crop up after release, or things that can still be improved. 

 We decided need to drop `WBootstrap4Theme` unless there's actual demand for it. The expectation is that most people will just use the latest version. work on.