Download and create information for the DNN models used with OpenCV has been
moved from code to dnnmodels.conf.  The file uses standard .ini formatting.

Explanation of the file format:
[ModelName]
DisplayName=Display Name of the model to be used in the UI
ToolTip=ToolTip for the model to be used in the UI
Usage=valid options are face_detection, face_recognition, aesthetics, object_detection, and weights.  Can contain multiple values comma or pipe separated
Application=Application needing this file.  Options are digikam and showfoto.  Can contain multiple values comma or pipe separated
MinVersion=minimum digikam version needed to use the model
FileName=filename of the model.  Used for downloading the model and loading the model from disk
DownloadPath=path on the KDE download server
SHA256=SHA256 hash for download verification
FileSize=file size in bytes
DefaultThreshold=scale 0-100.  Default threshold to use when not set in the UI
MinUsableThreshold=scale 0-100.  Settings below this value return too many false positives
MaxUsableThreshold=scale 0-100.  Settings above this value exclude too many false negatives
LoaderType=DNN model type.  Valid options are net (for onnx, pb, tf), config, YuNet, and SFace
Preprocessor=image preprocessor to use.  Blank if not used. Values are Blob and Flat
Classifier=classifier to use on model result set
ClassList=Class list text file.  This file is given to the classifier to map class IDs to text labels 
ConfigName=name of the weights file if needed.  Blank if no weights file needed.  Must match another [ModelName] section
MeanValueToSubtract=Scalar value for tuning the model. 0,0,0 if not used
ImageSize=recommended image size to pass to the model for processing.  0 if not used


YOLOv3 example:

[YOLOv3]
DisplayName=YOLOv3
Usage=face_detection
Application=digikam|showfoto
MinVersion=8.5.0
FileName=yolov3-face.cfg
DownloadPath=facesengine/dnnface/
SHA256=f6563bd6923fd6500d2c2d6025f32ebdba916a85e5c9798351d916909f62aaf5
FileSize=8334
DefaultThreshold=70
MinUsableThreshold=20
MaxUsableThreshold=80
LoaderType=net
Preprocessor=Blob
Classifier=
ClassList=
ConfigName=YOLOv3_Weights
MeanValueToSubtract=0,0,0
ImageSize=412

[YOLOv3_Weights]
DisplayName=YOLOv3 Weights
Usage=face_detection
Application=digikam
MinVersion=8.5.0
FileName=yolov3-wider_16000.weights
DownloadPath=facesengine/dnnface/
SHA256=a88f3b3882e3cce1e553a81d42beef6202cb9afc3db88e7944f9ffbcc369e7df
FileSize=246305388
DefaultThreshold=0
MinUsableThreshold=0
MaxUsableThreshold=0
LoaderType=Config
Preprocessor=
Classifier=
ClassList=
ConfigName=
MeanValueToSubtract=0,0,0
ImageSize=0
