* Don't override members of subclasses
* Fix patching

Use run_cmd instead of subprocess.run.
Explicitly declare all known members.
Don't rebuild linker cache when building LIBRARY_PATH
Use isinstance instead of type()

* patches are only applied if they aren't applied already
* patch no uses -p0 so git diff patches must be adjusted

ArchiveArtifacts check a downloaded archive against a provided checksum.
The Archive is downloaded to cache/<name>/<name>.<format>.
The only suported format is tar.
ArchiveArtifacts can be used as sources of an Allocator.

The designated patchdir of an Allocator class is located at
src/allocators/<class name>