Adjusted the definition of the explicit conversion on class types.
Adjusted the definition of the explicit conversion on class types.

[reviewed by Tom]

The change+clarification is championed by Kyle and Brad.

While there, clarified that explicit conversions are allowed
to the same target type.


git-svn-id: 88467cb1fb04b8a755be7e1ee1026be4190196ef@22380 3a8e244f-b0f2-452b-bcba-4c88e055c3ca

chizarlicious/chapel,chizarlicious/chapel,chizarlicious/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,hildeth/chapel,hildeth/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,sungeunchoi/chapel,chizarlicious/chapel,hildeth/chapel,sungeunchoi/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,chizarlicious/chapel,hildeth/chapel,chizarlicious/chapel,hildeth/chapel,sungeunchoi/chapel,sungeunchoi/chapel,hildeth/chapel,hildeth/chapel,chizarlicious/chapel