FMSLogo Code

Add a regression test that you can open and open file, provided that the subsequent filename has a different case than the original.

Centralize the logic for invalidating a rectangle in a way that honors the zoom factor and scroll positions.

Make the core logo code buildable with a Microsoft compiler.

Move some OWL-specific classes from main.cpp to mainwind.cpp.

Make logomath.cpp compile/link with non-Borland compilers.

Refactor header files so that init.cpp can be compiled into the screensaver.

Fix typo in #error

Fix location of declarations for functions in devwind.h and graphwin.h.

Fix location of declarations for functions in dlgwind.h and netwind.h.

Rename MAXINT to FIXNUM_MAX so that it doesn't conflict with the symbol defined in windows.h. This is being done as part of a refactoring effort to get the Logo language engine to compile with a recent Microsoft compiler.