wxProcess::open does not work under windows (the process stays in background mode), wxExecute is still used under windows
Minor other changes

* MinGWResourceCompiler: change output directory and name of compiled resource file (old resource object files have to be deleted manually, eg. cvpcb/cvpcb_rc.o since the 'make clean' target does not remove them).
* Add some comments.

* Set a NAME_RESOURCES variable in MinGWResourceCompiler.
* Fix looking for zlib under msys (C:\msys\1.0). Minizip now builds under windows with external zlib.

eeschema: code cleaning. SCH_ITEM class used for all schematic items in eeschema. Files reorganization.

* Add mingw_resource_compiler macro (Win32).
* Fix windres wxWidgets include paths (Win32).

Added calls to TestDanglingEnds() at undo and redo, so dangling ends are correctly updated (e.g. when a compnent deletion is undone).

Solved: eeschema crashes when create a new sheet. Added comments in gestfich.cpp to explain the default paths used by kicad to find help files and lib files

Fixed redrawing of dangling ends when connecting segments (not-anymore-dangling-ends were still displayed).

Fixed Drawing of DrawSheetStruct, so DrawSheetLabelStructs are only drawn if they are not being moved (fixes ugliness while moving PinSheets).

Added GetBoundingBox() for DrawNoConnectStruct, DrawBusEntryStruct. Removed old XOR method form DeleteStruct().