* generator/*.cs: add DefaultValue prop for obtaining a
sane value when we need to return a value but something bad has
happened such that we can't get a real value. Needed for iface
signal marshaling, among other places we're partially working
around it now.
svn path=/trunk/gtk-sharp/; revision=86157
* generator/AliasGen.cs : derive from SimpleBase.
* generator/ConstStringGen.cs : derive from SimpleBase.
* generator/GObjectGen.cs : kill. now uses ManualGen.
* generator/GStringGen.cs : kill. now uses MarshalGen.
* generator/GUnicharGen.cs : kill. now uses MarshalGen.
* generator/LPGen.cs : derive from SimpleGen.
* generator/Makefile.am : update source files.
* generator/ManualGen : make this general for handle types.
* generator/MarshalGen : new CallByName/FromNative formatter class.
* generator/SymbolTable.cs : needed some reorganizing and some
restructuring of types to use MarshalGen.
* generator/TimeTGen.cs : kill. now uses MarshalGen.
svn path=/trunk/gtk-sharp/; revision=38109