Have per-style max. bounding box limits

[hholzgra]

Right now there is only one global bounding box size limit, mostly meant to prevent out-of-memory situations.

Different styles have different memory consumption though, with e.g. the "Pencil" style being very "memory hungry".

So in addition to the global size limit it should also be possible to set per-style limits in the configuration style, with the effecting bounding box limit being the minimum of global and style specific settings.

Maybe we could also have a "max size scale factor" instead, e.g. "this still allows for only 10% of the global bounding box width / height limit.