can you add an argument 'sample_weight_test' in the defination of RandomForestRegressorWithWeights

[qingnanl]

Hello developers,

Many thanks for your great work iRF; it has great potential in many application scenarios. While I was working on a regression problem, I noticed that when I tried to use RandomForestRegressorWithWeights, an argument (although default None) 'sample_weight_test' was passed to RandomForestRegressorWithWeights, while it was not defined in RandomForestRegressorWithWeights. This caused an error of TypeError: fit() got an unexpected keyword argument 'sample_weight_test'. I think it could be simply resolved by adding an argument 'sample_weight_test' in the defination of RandomForestRegressorWithWeights, as many won't really give any test sample weights at all.

Many thanks,
Qingnan