Investigate porting to GtkRadiant 1.6

[neogeographica]

It's the wave of the future. Probably some interesting architectural differences that will make me change everything!

[neogeographica]

Some notes on the current plugin dependencies on Radiant interfaces and data structures:

PluginModule.{cpp,h} and PluginRegistration.cpp have all sorts of dependencies
(New plugin registration for 1.6 uses Synapse_EnumerateInterfaces)

Many files use templates from libs/generic/callback.h:
  BindFirstOpaque2, BindFirstOpaque3, Callback1, Callback2, Callback3, MemberCaller1, PointerCaller1
And a template from libs/generic/referencecounted.h:
  SmartPointer

GenericPluginUI.cpp
  qerplugin.h
    GlobalRadiant().m_pfnMessageBox
    eMB_OK, eMB_ICONERROR, eMB_ICONWARNING, eMB_ICONDEFAULT defines

MeshEntity.cpp
  ishaders.h
    IShader type
    GlobalShaderSystem.getShaderForName
  libs/texturelib.h
    qtexture_t type

MeshEntity.h
  libs/scenelib.h
    FLT_MAX define (in MeshEntity.cpp)
    scene::Instance type (in MeshVisitor.cpp)
    Node_isPatch (in MeshVisitor.cpp)
  ipatch.h
    Matrix type
    GlobalPatchCreator().Patch_getControlPoints, Patch_getShader, Patch_undoSave, Patch_controlPointsChanged (in MeshEntity.cpp)

GeneralFunctionDialog.cpp
  iundo.h
    UndoableCommand

MainMenu.cpp and SetScaleDialog.cpp
  iselection.h
    GlobalSelectionSystem
  iundo.h
    UndoableCommand

AllocatedMatrix.h
  ipatch.h
    Matrix type

MeshVisitor.h
  iselection.h
    SelectionSystem::Visitor type