[Sdb] Debugger stepping like .Net

3 commits...
* [Sdb] Set filter on ss_req in ss_create
 * See commit message
* [Sdb] Removed exclusion of CEE_POP and CEE_NOP sequence point creation
  * Is mostly also self explaining via XS unit tests and also manual stepping I came to conclusion this sequence points are also needed
* [Sdb] Removed STEP_SIZE_LINE logic(because it's useless and unlogical…
  * Removed in this commit is STEP_SIZE_LINE because this stepping was used only because STEP_SIZE_MIN didn't work correctly until now...
  * So what new code is doing is checking if we are in same method as when we started stepping and if we are and we stepped on NONEMPTY_STACK sequence point we continue stepping. This has same effect as [.Net StepRange](http://msdn.microsoft.com/en-us/library/ms232470%28v=vs.110%29.aspx)