Parse and display EID's in their proper string form

+ Add Entry.EIDString
+ Add Entry.EIDToString
Fix checkpoint rendering in EntityEntryViewer
Reverse the vertex order in OldSceneryPolygon (it was wrong)
Add support for exporting scenery to OBJ format

+ Add OldSceneryEntry.ToOBJ
+ Add FileUtil.OBJFilter
Move FileUtil filters to FileFilters class
Use "params" for FileUtil method filters
Fix warnings in CrashEdit/Resources.cs