Modified the class so that one can enumerate all the formats, i.e., vbCFText, vbCFBitmap, etc, that exist on the clipboard or data object

New methods

1) FormatCount: returns number of formats

2) GetFormatAttrs: returns the format's ID and Name as appropriate
- accepts an Index from 1 to FormatCount
- returned FormatID is usable for any class or VB method that requires a ClipBoardConstants value
- returned FormatName is the string used to register the format for custom clipboard formats. Standard formats return the windows constant used for that format

3) pvEnumFormats and pvAddFormat are helper functions
- pvEnumFormats shows low-level COM example of retrieving the IEnumFormatETC class & using it's virtual methods