Loosening the tolerance used for judging a spurious/duplicate root.

This fix loosens the tolerance (htol) used in roots@chebfun for determining if a root is spurious/duplicate when it is close to another root. The current tolerance introduced by commit b704d284 is a bit of too tight, causing a few failures in tests for min, minandmax, etc when 1st-kind points are used. By loosening the current tolerance by a factor of 10, the failures or crashes related to this issue are all gone.

All tests passed with 2nd-kind points at the same time.