* Encapsulate file name member of base screen object.
* Encapsulate associated screen member of schematic sheet object.
* Create add screen method to schematic sheet object to simplify setting
the associated screen.
* Move the change file name code in the schematic sheet object to the edit
sheet method in the schematic editor frame object to eliminate message
dialogs.
* Improve reference counting in schematic screen object.
* Add helper type definitions for changing schematic object storage to C++
containers.
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+eeschema
* commiting my changes to allow multiple instances of a given schematic file within
a hierarchy:
** internally, m_currentScreen has been replaced with m_currentSheet,
which is a list or 'path' of screens. The path of screens is used to
generate
a series of timestamps, which is converted to flat component reference via
a look-up
table in the schematic files.
** this means that m_currentScreen is no longer used -- use GetScreen().
** GetScreen is virtual, as some of the dialogs keep around a WinEDA_BaseScreen
pointer.
** all sub-sheets in a given schematic must have different names to generate a
meaningful netlist.