collection: use the biji item book property

The book property was not working anymore.
Fixes 709820
Tomboy notes: be sure not to alter source

See 708812
New classes: BijiImportProvider, BijiTomboyReader
Instead of directly creating a note from an existing file
(then altering path and saving...), read the data, instanciate
an object then save it as anyone would expect.
tomboyReader: cleanup: append html header at gstring initization
tomboyReader: do not fail on html reserved characters

See 708812
ownCloud: add a bit for import
Prepare for 3.10.1