Enable Underscore Package, Attribute and Operation names

[sschwindt]

Any use of underscores of a package, attribute or operation name cannot be interpreted by Latex and standard packages, such as \underscore, cannot resolve the issue. As a workaround, embracing arguments #1 and #2 with \detokenize{} in tikzlibraryumlcd.code.tex works for attributes and operations, but cannot be implemented easily for packages. Adding such capacity would be great because underscores are commonly used in Python for package, attributes, and operations.

[EagleoutIce]

There is a similar problem with using a comma (e.g., for Java generics) and \implement. However, this can be solved manually like this:

   \draw[umlcd style implement line] (node cs:name={A<K,V>}) -- (node cs:name={B<K,V>});