Fix acceleration bug where an extruder only move was though to be a real move and uninitialized fields were being used to calculate trapezoids
Fix partial memory leak where the blocks gocde vector was not being cleared when it was popped from the tail
rename RingBuffer::delete_first() to delete)tail() to reflect what it actually does
Merge pull request #306 from wolfmanjm/upstreamedge

Fix acceleration bug, and memory leak