All egs++ shapes should be converted to shared libraries

[rtownson]

A few simple shapes are defined with type= instead library= and this can be confusing for users. The shapes might as well be made available as shared libraries just like the rest.

[ftessier]

Agreed. This is always a nuisance, even for experienced EGSnrc users! We can check whether this affects efficiency, but I presume it won't have a significant impact. Is there any mention in the docs why it was done this way in the first place?