Idea: make the GAP break loop (optionally) available for debugging

[fingolfin]

When writing and debugging GAP code, the break loop is an essential feature.

In Oscar, we don't have it, as we work hard on "hiding" it.

Perhaps we shouldn't, and instead, enable the break loop -- at least optionally, i.e. have a way for the user to enable/disable it.

I don't know yet how this could work, or if it can work at all, but after having learned that there is a Julia package which kinda retrofits a break loop into Julia (see https://github.com/JuliaDebug/Infiltrator.jl) I now want to have it back for GAP in Julia, too :-)

[mohamed-barakat]

This would be a wonderful feature 😄