0.18.3

Highlights:

[ea6cedd] Process sidebar directive's titles as span nodes
[95b11a3] Add support for fake browser decoration in images
[d53d4b7] Add a wrapper element for tables
[205c0b0] Update the style of versionadded and deprecated admonitions
[5493a49] Expose console as a real Composer binary
[293c45d] Prepare support for doctrine/rst-parser: 0.5