Fixed bug by not inheriting SolElement.
Fixed bug by not inheriting SolElement.

- If SolCorElement inherits from SolElement, instance of SolCorElement
  is also instance of SolElement, that way, some 'if' routines cannot
  precise locate the correct class type, the solution here is create
  SolCorElement just inherit from Element.

archman/phantasy,archman/phantasy