Remove DPI scaling on graphicsview fonts

It works better than setpixelsize and bundled font.

gui/theme.py:
 - fixDPI:
   Multiply font size with 72/DPI to get same size on all platforms.

Also removed LiberationSans fonts.

vistrails/gui/theme.py

@@ -307,37 +307,22 @@ def __init__(self):
 
         #### FONTS ####        
         # Font for module text
-
-        # Using "Liberation Sans" and pixelSize to get same look on all platforms
-        QtGui.QFontDatabase().addApplicationFont(
-            vistrails.core.system.vistrails_root_directory() +
-            '/gui/resources/fonts/LiberationSans-Regular.ttf')
-        QtGui.QFontDatabase().addApplicationFont(
-            vistrails.core.system.vistrails_root_directory() +
-            '/gui/resources/fonts/LiberationSans-Bold.ttf')
-        GRAPHICS_FONT = "Liberation Sans"
-        self.MODULE_FONT = QtGui.QFont(GRAPHICS_FONT, -1, QtGui.QFont.Bold)
-        self.MODULE_FONT.setPixelSize(14)
-        self.MODULE_FONT.setHintingPreference(QtGui.QFont.PreferNoHinting)
+        # Use fixed dpi to get same font size on all platforms
+        def fixDPI(i):
+            return i*72/QtGui.QApplication.desktop().logicalDpiY()
+        GRAPHICS_FONT = "Arial"
+        self.MODULE_FONT = QtGui.QFont(GRAPHICS_FONT, fixDPI(14), QtGui.QFont.Bold)
         self.MODULE_FONT_METRIC = QtGui.QFontMetrics(self.MODULE_FONT)
-        self.MODULE_DESC_FONT = QtGui.QFont(GRAPHICS_FONT, -1)
-        self.MODULE_DESC_FONT.setPixelSize(12)
-        self.MODULE_DESC_FONT.setHintingPreference(QtGui.QFont.PreferNoHinting)
+        self.MODULE_DESC_FONT = QtGui.QFont(GRAPHICS_FONT, fixDPI(12))
         self.MODULE_DESC_FONT_METRIC = QtGui.QFontMetrics(self.MODULE_DESC_FONT)
-        self.MODULE_EDIT_FONT = QtGui.QFont(GRAPHICS_FONT, -1)
-        self.MODULE_EDIT_FONT.setPixelSize(10)
-        self.MODULE_EDIT_FONT.setHintingPreference(QtGui.QFont.PreferNoHinting)
+        self.MODULE_EDIT_FONT = QtGui.QFont(GRAPHICS_FONT, fixDPI(10))
         self.MODULE_EDIT_FONT_METRIC = QtGui.QFontMetrics(self.MODULE_EDIT_FONT)
 
         # Font for version text
-        self.VERSION_FONT = QtGui.QFont(GRAPHICS_FONT, -1, QtGui.QFont.Bold)
-        self.VERSION_FONT.setPixelSize(15)
-        self.VERSION_FONT.setHintingPreference(QtGui.QFont.PreferNoHinting)
+        self.VERSION_FONT = QtGui.QFont(GRAPHICS_FONT, fixDPI(15), QtGui.QFont.Bold)
         self.VERSION_FONT_METRIC = QtGui.QFontMetrics(self.VERSION_FONT)
-        self.VERSION_DESCRIPTION_FONT = QtGui.QFont(GRAPHICS_FONT, -1,
+        self.VERSION_DESCRIPTION_FONT = QtGui.QFont(GRAPHICS_FONT, fixDPI(15),
                                                     QtGui.QFont.Normal, True)
-        self.VERSION_DESCRIPTION_FONT.setPixelSize(15)
-        self.VERSION_DESCRIPTION_FONT.setHintingPreference(QtGui.QFont.PreferNoHinting)
         self.VERSION_DESCRIPTION_FONT_METRIC = \
             QtGui.QFontMetrics(self.VERSION_DESCRIPTION_FONT)