new DatContainer property: DataSectionDataLength - length of actual data in data section
changed all offsets to int type. 2Gb is enough
changed property name in DatRecordFieldInfo
name of top GGPK directory is now "ROOT"
new class: DataReader, which helps to read data section entries
renamed DatContainer function: GetBytes > SaveAsBytes
updated GetCSV() function in DatContainer

- it now uses GetCSVString(...) function to get field value formatted for CSV
added to DatRecordFieldInfo property that contains C# type of data that can be read using field offset.
[UI][Release] many changes: Lazy TreeView, option to delete TreeView Item

- TreeView now loads lazily (only when directories are expanded)
- context menu has new option: Deltee, which deletes TreeViewItem under it. For now it doesn't delete record in GGPK() instance
- TreeView is virtualized
- MainWindow.xaml.cs: code reformattied and cleaned, some methods renamed and moved.