commit: revision marks fix

[Tomas Frydrych]

fixed the delete problem noted by Martin, changed default focus in 
the win32 MarkRevisions dialogue.

files: pt_PieceTable.h, pt_PT_DeleteSpan,cpp, fv_View*.cpp, 
fl_BlockLayout.cpp, pd_Document.h/cpp, 
ap_Win32Dialog_MarkRevisions.cpp

Tomas