songs.sqlite will not be downsized when deleting songs

[rimach]

Do the following steps for easy reproduction. (tested on windows)
1. rename songs.sqlite to songs.sqlite.orig
2. start openlp
3. import songs.sqlite.orig
4. close openlp
5. See in filemanager -> sizeof songs.sqlite
6. do the same steps 2-5 -> size of songs.sqlite is grown (thats correct)
7. start openlp
8. clean all double entries (because of they all existing twice after the second import)
9. close openlp
10. See in filemanager -> sizeof songs.sqlite => its the same size as step 6 (but, we have only the half of entries now???)

[rimach (crichter)]

Oh I forgot:
11. After renaming the database from step 10, restarting OpenLP and import the database, we have the correct filesize from step 6

[Raoul Snyman (raoul-snyman)]

This is the way SQLite works by design. We'll need to run the VACUUM command every now and then. I don't actually see the need for this, as disk space is cheap.