Tempsdb

* added `disable_mmap`, `enable_mmap` and `open_chunks_mmap_size` into `VarlenSeries`

* added multiple properties and attributes to `VarlenSeries`

* added `VarlenSeries.close_chunks`
* `Database.sync` will now return 0
* indexed-gzip proved to be a poor choice, dropped
* `setup.py` fixed

* if mmap is used, the kernel will be informed after loading the chunk that we
don't need it's memory right now
* deleting a `TimeSeries` will now correctly return a zero
* both `Database`, `TimeSeries` and `Chunk` destructor will close and
emit a warning if the user forgot to
* if page_size is default, it won't be written as part of the metadata
* added support for per-series metadata
* following additions to `Database`:
* `delete_series`
* `delete_varlen_series`
* following additions to `TimeSeries`:
* added `append_padded`
* added metadata support, `metadata` property and `set_metadata` call
* added variable length series
* added experimental support for gzipping time series
* fixed a bug where getting a series that was already closed would TypeError
* following additions to `Chunk`:
* `get_slice_of_piece_at`
* `get_slice_of_piece_starting_at`
* `get_byte_of_piece`
* `get_timestamp_at`
* fixed the behaviour of `AlternativeMMaps` when passed a single index to __getitem__ and __setitem__
* added `StillOpen` exception, chunk won't allow to close itself if it has any
remaining references

* iterating and writing at the same time from multiple threads
made safe
* added `TimeSeries.disable_mmap`
* `Iterator`'s destructor will emit a warning if you forget to close it explicitly.

* empty series will return an Iterator
* **bugfix release** fixed `Database.create_series`
* `Database` constructor will throw if no database is there
* changed `Iterator.next` to `Iterator.next_item`,
synce Cython guys said to not implement the method `next`
on iterators.