Command
QisLib_GetDataNumberPerLayer

QisLib_GetDataNumberPerLayer

Function:
	int QisLib_GetDataNumberPerLayer(CQisLayerData** ListPtr);

Inputs:
	ListPtr: Address of a pointer of type CQisLayerData*. When the function returns
	successfully, this pointer will point to a list of items, each of type
	CQisLayerData.

Return:
	success: value > 0 indicating the number of items in the list.
	special: 0 indicating no layers were found or no GDSII/OASIS file open.
	failure: value < 0 indicating one of the following errors :

Errors:
	-1: Input argument is invalid (null).
	-2: No GDSII or OASIS file has been opened.
	-3: Internal memory error occurred.
	-4: File open in progress, operation not permitted.

Description:
	- This function returns a list of layers and the number of boundaries, paths, texts
	and boxes present on each layer.
	- For OASIS files, number of boxes is 0 since there are no boxes in OASIS files.
	- The list does not contain information on a per datatype basis. Hence each item in
	the list contains information for all datatypes associated with a particular layer.
	- It is the responsibility of the user to free the memory allocated to the list using
	QisLib_FreeLayerDataList.

Example:
	CQisLayerData* List;
	Ret = QisLib_GetDataNumberPerLayer(&List);
	...
	QisLib_FreeLayerDataList(List);