TODO doc for Pango namespace.

There are in total 76 xml to document in Pango. Right now there are 63 xml not documented in any proportion.
The idea is to have a easy way to know what documentation is missing, if you want to help or are helping please take out the xml that you commit
from the missing list. For documentation that take some time to finish (like HTML, TextBuffer, etc) the best is that you but your name and email
next to the file in this list to acknowledge that you are working in it (is recommendable that you suscribe to the mono-docs  mailing list).

Following is the list of undocumented xml:

Analysis.xml
Attr.xml
AttrClass.xml
AttrColor.xml
AttrFilterFunc.xml
AttrFloat.xml
AttrFontDesc.xml
AttrInt.xml
AttrIterator.xml
AttrLanguage.xml
AttrList.xml
AttrShape.xml
AttrString.xml
Attribute.xml
Color.xml
Context.xml
Coverage.xml
Engine.xml
EngineInfo.xml
EngineLang.xml
EngineRange.xml
EngineShape.xml
FT2FontMap.xml
FT2SubstituteFunc.xml
Font.xml
FontDescription.xml
FontFace.xml
FontFamily.xml
FontMap.xml
FontMetrics.xml
Fontset.xml
FontsetSimple.xml
FreeGCFunc.xml
GetGCFunc.xml
Global.xml
GlyphGeometry.xml
GlyphInfo.xml
GlyphItem.xml
GlyphString.xml
GlyphVisAttr.xml
IncludedModule.xml
Indic.xml
IndicScript.xml
IntSet.xml
Item.xml
Language.xml
Layout.xml
LayoutIter.xml
LayoutLine.xml
LayoutRun.xml
LogAttr.xml
Map.xml
MapEntry.xml
OTInfo.xml
OTRuleset.xml
Rectangle.xml
Scale.xml
TabArray.xml
Win32FontCache.xml
X.xml
XFontCache.xml
Xft.xml
XftSubstituteFunc.xml