Merge pull request #169 from ivanlanin/#160-refactoring

#160 refactoring: Merge TableFull-Table Style + Merge MemoryImage-Image
Update README.md, docs, and version number
Merge pull request #176 from ivanlanin/develop

Update README.md  #174, docs, and version number
Revert project name capitalization #176
Merge remote-tracking branch 'upstream/develop' into develop
Merge pull request #177 from PHPOffice/develop

Version 0.9.0
Update README.md

Change link to RTD.
#160 Rename folder: Section > Element; Exceptions > Exception
Fix psr-4 base dir in composer.json
Updated change log
Moved the autoloader in the basic usage to the installation section in the read me
New `Container` abstract class
Flatten Element folder
Merge remote-tracking branch 'upstream/develop' into #160-refactoring