A trait providing an optional cache for classpath entries obtained from zip and jar files.
It's possible to create such a cache assuming that entries in such files won't change (at
least will be the same each time we'll load classpath during the lifetime of JVM process)
- unlike class and source files in directories, which can be modified and recompiled.
It allows us to e.g. reduce significantly memory used by PresentationCompilers in Argus IDE
when there are a lot of projects having a lot of common dependencies.