Added missing params display and render blocks

Missing $useBlocks params in `displayBlock(`) and `renderBlock()` methods causing infinite loops in certain Twig rendering scenarios.
Removed invalid call that shouldn't be used anyway

Is intended for testing only anyway
Revert "Removed invalid call that shouldn't be used anyway"

This reverts commit 6af2ea47318455cb51f7838a6a3f123db5fde4e4.
Merge pull request #164 from getgrav/master

Added missing params display and render blocks