Package cleaner should replace hyphens with underscores

[chrylis]

When the package name for a project contains hyphens, these are squashed (as hyphens are not legal characters), but it would be a bit clearer if they were replaced with underscores instead of the current removal, which is the official naming recommendation

[rosennej]

The same applied for package names generated automatically. Our web address is qsm-fss.com, so according to the rules we use com.qsm-fss in the Maven group, and expect com.qsm_fss in the generated package name. But the generated MD says: "* The original package name 'com.qsm-fss.sb-demo.demo' is invalid and this project uses 'com.qsmfss.sbdemo.demo' instead."