Added optional use of igbinary if installed
Update ServiceProvider.php
Added missing import
Update ProjectDescriptorMapper.php
Update ProjectDescriptorMapper.php

@mvriel This sounds strange to me because it is working on my project i had tests with. But if the project descriptor is not populated with data my first version just overwritten the cache with empty values then? so maybe it will be better to clear the cache if the value couldnot be unserialized. what do you think?
Update ProjectDescriptorMapper.php
Change definition of summary/description break

In this commit I have made the following documentation changes:

- Changed short description to summary
- Changed long description to description
- Changed example mail address
- Changed definition when a summary breaks and becomes a description
  to match PSR-5 and actual usage.
Integrated code review feedback
add test for FileDescriptor.php
Added unit test for Statistics::transform
Also tested the Statistics::transform method with a different starting artefact.
Updated for PSR-2
Add tests for Descriptor\Filter (PFZ TestFest)
Unit tests code Descriptor/Reflector coverage
finalizing FileDescriptorTest while finishing testGetAllErrors()
Refactored the StatisticsTest for better reuse.
Merge pull request #1368 from choonge/FilterTest

Add tests for Descriptor\Filter (PFZ TestFest)
Added two validator tests

Written during amsterdamPHP TestFest
tests/unit/phpDocumentor/Plugin/Core/Descriptor/Validator/Constraints/Classes
is now complete
add parser encoding to reference documentation
Merge pull request #1374 from gimler/patch-2

add parser encoding to reference documentation