improves pinyin_get_pinyin_strings
add checks for add phrase function
add comments
write add_pronunciation
fixes test_memory_chunk.cpp
update test_parser2.cpp
update spseg.cpp
update ngseg.cpp
update gen_binary_files.cpp
update gen_chewing_table.cpp
rename gen_chewing_table.cpp to gen_pinyin_table.cpp
polish code
update estimate_k_mixture_model.cpp
update export_k_mixture_model.cpp
update test_phrase_lookup.cpp
update gen_deleted_ngram.cpp
update gen_k_mixture_model.cpp
update gen_ngram.cpp
update import_k_mixture_model.cpp
update merge_k_mixture_model.cpp