Removed : version of the composer.json
Added support for Groups in PowerPoint.
- Also supports correct extent and offset calculations in PPT Slides.
Merge branch 'develop' of github.com:pr0phet/PHPPowerPoint into develop

Conflicts:
	CHANGELOG.md
Matching code style of PHPPowerPoint for if's and foreaches.
Fixing bugs in the PHPDoc changes I made.
More code style cleanup.
Last bit of code style cleanup.
Fixing Travis errors:
- https://travis-ci.org/PHPOffice/PHPPowerPoint/jobs/42919909#L297
- https://travis-ci.org/PHPOffice/PHPPowerPoint/jobs/42919909#L320
Added Group support for ODPresentation classes.
Fixed bug wherein grouped pics weren't included in the pptx.
Fixed bug wherein hyperlinks within groups were not functional
Merge remote-tracking branch 'upstream/develop' into develop

Conflicts resolved:
	src/PhpPowerpoint/Writer/PowerPoint2007/Rels.php
Merge pull request #68 from pr0phet/develop

Adding Group support for PowerPoint2007.