Changing the way we modify version numbers. Now up the version before any commits for the respective
release go in. Makes a lot more sense, doesn't it? Starting 0.7 right here!
On startup, clean up leftover upload zip files. In practice this should never be necessary,
but we've seen a case where it did and caused trouble. So, let's just do it.
Add import function: Now a zip archive containing a valid MASLO project can be imported.
Such a valid zip archive can be obtained by using the export function, for example (to come).