Fix various issues under Windows (MSVC) * gui/msvc-debug.pri: New file to enable debugging in release mode. This is required to avoid mixing different VC++ runtime DLL. * gui/octave-gui.pro (QMAKE_LIBDIR): New variable containing octave library path. (LFLAGS): Remove, deprecated by QMAKE_LIBDIR addition. (win32-g++): Renamed win32 conditional with mingw-specific flags. (win32-msvc*): Include msvc-debug.pri, define required scintilla flag and use console mode (for the time being). * gui/src/lexer/lexeroctavegui.h (class LexerOctaveGui): Remove wrong QSCINTILLA_EXPORT decorator.

new file mode 100644
--- /dev/null
+++ b/gui/msvc-debug.pri
@@ -0,0 +1,8 @@
+win32-msvc* {
+	CONFIG += release warn_off
+	QMAKE_CXXFLAGS += -MP
+	QMAKE_CXXFLAGS_RELEASE += -Zi
+	QMAKE_CXXFLAGS_RELEASE -= -O2
+	QMAKE_LFLAGS_RELEASE += -debug
+	QMAKE_CLEAN += $(DESTDIR)$(QMAKE_TARGET).pdb
+}