Memory searching / Status bar for debug utility / Lots of other stuff

Search is currently hardcoded to forward + wrap.

The small stuff:

Refactoring
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* Split the debug window into a parent and child window to accommodate the status bar.
  To eliminate window handle confusion, most helper functions take only the NP2VIEW_T as parameter now.
* Move duplicated subwindow message handling to np2class.cpp
  Emulation should now pause much more consistently :-)
* viewmem: Calculate byte and char draw positions globally in viewmem_init() to remove duplication in WM_LBUTTONDOWN / viewmem_paint()
* Move validhex() to milstr... that's the only more global place where it makes sense
* Convert filenames in np21.vcxproj to lowercase.
  The filters are still a mess though. What a redundant and bloated design.

Redesign
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* Reorder menu items in debug window

New features
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* Add milstr_solveHEXbuffer to convert hex strings of arbitrary length to bytes