Add new model for customized fit function

Analyser/FitAnalyser.py

@@ -224,6 +224,19 @@ class TwoGaussian2dModel(Model):
         return pars
 
 
+class NewFitModel(Model):
+    
+    def __init__(self, func, independent_vars=['x'], prefix='', nan_policy='raise',
+                 **kwargs):
+        kwargs.update({'prefix': prefix, 'nan_policy': nan_policy,
+                       'independent_vars': independent_vars})
+       
+        super().__init__(func, **kwargs)
+        
+    def guess(self, *args, **kwargs):
+        return self.make_params()
+    
+
 lmfit_models = {'Constant': ConstantModel,
                 'Complex Constant': ComplexConstantModel,
                 'Linear': LinearModel,