Fix issue with LSL jumps screwing up the C# compiler error -> LSL code position map and leading to invalid error line numbers/columns

This is because jump statement generation was mistakenly inserting its own line without updating the csharp positions in CSCodeGenerator.
This is Aleric Inglewood's patch in http://opensimulator.org/mantis/view.php?id=7195 but applied to opensim itself rather than the defunct code generation in opensim-libs.  Thanks!
This patch also adds a regression test for this case from myself.