Make single-line IFs open a scope
- otherwise variables declared within could be seen by the parent scope without necessarily being initialised, e.g. 'IF 0 THEN DIM s AS STRING ENDIF:  PRINT s'
Fix NMPGSCROLL structure in win/commctrl.bi, as described in http://www.freebasic.net/forum/viewtopic.php?p=183737#p183737
Fixup some changelog changes from 90130b19