Update package to 3.1.5.
Changes since 3.0.10:
3.1.0: Added support for data table formulae; Rich Text in cells; Custom
Document Properties; mapped chartspace graphical properties to charts.
Breaking: removed deprecated workbook methods (get_named_range,
add_named_range, remove_named_range) and several worksheet properties.
Bug fixes: fixed table filters being overridden, various dataframe and
multiindex alignment issues.
3.1.1: Fixed DocumentProperties times being set only at module import;
fixed missing worksheet-specific definitions.
3.1.2: Fixed reading worksheets in read-only mode with locally scoped
definitions; fixed empty custom properties causing invalid files.
3.1.3: Major performance fixes -- column name caching, pivot table
loading, custom properties reading; fixed rich-text save without lxml;
fixed file handler leaks; fixed timedelta reading in read-only mode;
improved duplicate named styles handling.
3.1.4: Minor bug fixes and stability improvements.
3.1.5: Latest stable release with cumulative fixes.
Add test.sh to verify write/read roundtrip of xlsx workbooks.
Signed-off-by: Alexandru Ardelean <alex@shruggie.ro>
