Blender Git Loki

Fix T40007 Bevel tool resets after getting to 1.

If the side of a beveled edge hit another vertex, the offset
amount reset to zero. This was the result of commit rB1582dd5e4d7c
which clamped the amount to zero to avoid creating spikes with
obtuse angles. Now we clamp the amount to the closest end of
the edge to where the amount wants to be.
Also fixes the first part of T40365.