mvn_artifact: check if extensions match
TODO: remove "mvn_artifact" feature
Add tests for extensions in mvn_artifact
TODO: remove "tests for mvn_artifact"
maven_depmap_test: remove unused variable
todo: expand lonely maven_depmap tests
mvn_file: add support for absolute paths

Absolute paths will be converted to relative based on prefix ("/usr/share/java"
by default).  This can be used even for SCLs when prefix is changed
todo: add tests for mvn_file wrt prefix usage and relative paths
xmvn_config: add support for custom xml options