Added Lines Before Namespace Fixers

NoBlankLinesBeforeNamespaceFixer is a contrib level fixer, and OneBlankLinesBeforeNamespaceFixer is a symfony level fixer. This also includes some utils refactoring and improvements.
> countLines is a new method in this PR, which isnt merged, so you can change it

to what?

> splitLines() is existing method, rename should happen in 2.0, current method could be marked as deprecated

no point - just straight rename it at 2.0