Fix 25245 - Line hooks not saved.

If begin or end hooks are turned on, but their size and type properties are not changed, the hooks themselves are not saved.

See http://musescore.org/en/node/25245 for details.
Fix libmscore/copypaste tests
Fix capella/io tests
Merge pull request #831 from mgavioli/fix_25245_line_hooks_not_saved

Fix #25245 - Line hooks not saved.