[Fontconfig] Another proposal for saving custom fonts in fontconfig

[Peng Wu]

Hi,

  Here are another proposal for the XML syntax, which try to
re-use the current fontconfig XML syntax.

'''
<fontconfig>
<description>Custom Font: Variable Font Family Custom Style
Name</description>
<customefont>
	<origin>
                <test name="family">
                        <string>Variable Font Family</string>
                </test>
                <test name="style">
                        <string>Style Name</string>
                </test>
        </origin>
        <custom>
                <edit name="family" mode="assign">
                        <string>Variable Font Family</string>
                </edit>
                <edit name="style" mode="assign">
                        <string>Custom Style Name</string>
                </edit>
                <edit name="fontvariations" mode="assign">
                        <string>AXIS1=VALUE;AXIS2=VALUE</string>
                </edit>
	</custom>
</customefont>
</fontconfig>
'''

The above XML syntax will work like the previous example.

The "origin" XML element will only contain "test" element,
the "custom" XML element will only contain "edit" element,
the "description" XML element will only for maintenance purpose.

Feel free to comment it.

Thanks,
  Peng