[BUGFIX] Reset and Get the correct PipesOut
Merge pull request #398 from coding46/fix-1

[BUGFIX] Reset and Get the correct PipesOut
[BUGFIX] AbstractPipe class was not really an abstract class
Merge pull request #399 from coding46/fix-2

[BUGFIX] AbstractPipe class was not really an abstract class
[TASK] Remove clearing of files belonging to Flux's old autoloader
[TASK] Completely stop drawing preview when Provider says so
[TASK] Move a thrown Exception to point where class is used
[TASK] Make Flux a top priority extension
[TASK] Enclose core registrations with class check

Although this might be temporary, it prevents a certain case of installing on 6.2 when Flux has never been installed before, which causes a "class not found" for FluidTYPO3\Flux\Core - this initial, cheap check prevents that horrible error by only performing registration once the class has been properly autoloader - which will happen when it gets checked if it exists, making it available on the very next page load.