GUI Updates (#2943)

[skin]
* add eRectangle processor
* add parseGradient
* rename scrollbarItemAlignment to itemAlignment attribute
* add new attributes : selectionZoom, itemSpacing, spacerColor

[eListbox]
* massive improvements and many new features
* improve paint and list invalidation
* add zoom and spacing support
* prepare more alignment options
* many perfomance improvements

[eListboxPythonMultiContent]
* add TYPE_RECT, TYPE_LINEAR_GRADIENT, TYPE_LINEAR_GRADIENT_ALPHABLEND
* add zoom and spacing support

[eListboxServiceContent]
* small changes to fit the new listbox style 

[eListboxServiceContent]
* small changes to fit the new listbox style 

[gPixmap/gPainter]
* add drawGradient

[ePixmap]
* add gradient support

[eSlider]
* add pixmap scale support

[MultiContent]
* add MultiContentEntryRectangle , MultiContentEntryLinearGradient, MultiContentEntryLinearGradientAlphaBlend

Co-authored-by: @zKhadiri

lib/gdi/Makefile.inc

@@ -5,6 +5,7 @@ gdi_libenigma_gdi_CXXFLAGS = $(LIBSDL_CFLAGS)
 gdi_libenigma_gdi_a_SOURCES = \
 	gdi/accel.cpp \
 	gdi/bcm.cpp \
+	gdi/color.cpp \
 	gdi/compositing.cpp \
 	gdi/epng.cpp \
 	gdi/erect.cpp \
@@ -25,6 +26,7 @@ gdi_libenigma_gdi_a_SOURCES = \
 gdiincludedir = $(pkgincludedir)/lib/gdi
 gdiinclude_HEADERS = \
 	gdi/accel.h \
+	gdi/color.h \
 	gdi/compositing.h \
 	gdi/epng.h \
 	gdi/epoint.h \