Change profiling to an external installation of XHGUI
#979: Add Twig Cache to reduce compilation time
Fix fatal error introduced by a refactoring in 2.1
[#989]: Update monolog requirement to 1.6

phpDocumentor now uses the ErrorHandler of Monolog but that wasn't available
until 1.6. Given that the composer.json is locked on 1.4 we need to bump the
requirement to 1.6.
Merge pull request #990 from mvriel/989

[#989]: Update monolog requirement to 1.6
Merge branch 'develop' of github.com:phpDocumentor/phpDocumentor2 into develop
Stable version constraints for all dependencies

Also update dependency specs in composer.lock
Merge pull request #996 from tommygnr/stable-deps

Stable version constraints for all dependencies
Merge branch 'develop' of github.com:phpDocumentor/phpDocumentor2 into develop
Add unit test for the bootstrapping class
Remove unused data files
Refactor base event and remove deprecated material
Add test for DebugEvent
Update DocBlocks for events and add test for LogEvent
Add unit test for abstract events
Fix unit tests for Dispatcher
Finish last test for translations
Use correct file docblock
Add test for PreFileEvent