Code refactoring (#74)

* Don't reset model state and feature extractor on endpointing

* support passing decoding_method from commandline

* Add modified_beam_search to Python API

* fix C API example

* Fix style issues

sherpa-onnx/csrc/features.h

@@ -16,6 +16,7 @@ namespace sherpa_onnx {
 struct FeatureExtractorConfig {
   float sampling_rate = 16000;
   int32_t feature_dim = 80;
+  int32_t max_feature_vectors = -1;
 
   std::string ToString() const;