Change NamedColor to use OUString

Change-Id: Id84d761b33f12dfc50f980e61ab44565693f2e5a
Make it easier to add new color attributes to GetDocColors

Change-Id: I2098892fc44c7a8bde1eb30f6db1709e58925577
Change palette selection ComboBox to ListBox

Change-Id: Id844781c06e37d66f3eebac9d905c58a62682cb0