[BUGFIX] Incorrect class name alias in ExtendedViewHelperNode on 4.x

Fixes: #5
Merge pull request #6 from NamelessCoder/classaliases

[BUGFIX] Incorrect class name alias in ExtendedViewHelperNode on 4.x
[BUGFIX] Incorrect class name used in alias for ExtendedViewHelperNode
[TASK] Set proper TYPO3 core version dependency
Merge pull request #8 from NamelessCoder/classaliases

[BUGFIX] Incorrect class name used in alias for ExtendedViewHelperNode
Merge pull request #9 from NamelessCoder/emconf

[TASK] Set proper TYPO3 core version dependency
[DOC] Add code quality graphs to README.md